This is an interesting question. As a Soviet historian, I can only directly speak to the Soviet side of things, some one else may have a different opinion on the history of fascism.

You have picked up on a common thread in Soviet historiography. It has definitely fallen out of favor in the more current histories of the Soviet Union. The reason for this is not a simple "It is no longer true" or the "history has changed."

There has been a shift over the years, especially since the 1970s away from purely political history. This shift is considered a shift to "Social History" and a move away from the longue duree (long term) method of history. Longue Duree means "long term" but generally applies to the idea of Macrohistory, for example looking at the Soviet Union in the scheme of Russian history, or looking at the entire Soviet Union as a whole. Historians since then have often looked at more social history, looking at the outcomes to the average citizen, to specific regions, or ethnicities within the larger whole. This also meant historians began to look beyond just men in their history and shifted into looking at women too, (a very revolutionary thought).

There also exists a shift in who was conducting the history and what the goal of the history was. This is where we are specifically talking about the Soviet Union. Initial historians of the Soviet Union were often writing during the height of the Cold War, and were from the West (predominating the United States). These initial historians are termed as "Cold War Warriors." As the name implies they were fighting a war... against Communism. The history focused on the totalitarian model because it played into the larger narrative of the social zeitgeist at the time. It was seen that the Soviet Union was totalitarian because it contrasted against Democracy and "free enterprise" of the West. Historians that were part of this initial cohort are Robert Conquest, Richard Pipes, and Merle Fainsod (partially). Another important figure of this cadre was George Kennan who wrote "The Long Telegram" which shaped international policy of the United States vis a vis the Soviet Union.

The issue with this history is it often focused on the "Great Man" theory of history. Focusing on Vladimir Lenin and Joseph Stalin as titans, monoliths that everything was shaped by them alone. That their rule was absolute, and everything that happened during the period was their prerogative.

Then a very important woman stood up and asked "Why?" Sheila Fitzpatrick questioned the thinking of these early historians, their zeal, and their method of history. She was part of the larger "rethinking" of the Soviet Union in the late 1970s and early 1980s, as part of the aforementioned Social History movement. This cadre of historians are often described as "Revisionists." But unlike the bad way the term is used, this cadre did amazing things to look at all the history their predecessors discarded. Fitzpatrick was not alone and a swath of other noteworthy historians would be considered part of this section. Another big name and book was Stephen F. Cohen's "Rethinking the Soviet Experience."

While the revisions were looking at more social and more holistic in history towards the Soviet Union often were writing in response to the Cold War Warriors. They often fell into the same trap of the dialogue around the Soviet Union. This is also because simply both sides were drawing from the same small pool of available documents and sources. That is until the fall of the Soviet Union, where you get the final couple of cadres of historians. You get those who still lived and were educated during the Cold War, initial historians so early 90s until around the 2010s, and ultimately historians who never lived during the Cold War. Both are similar, but you begin to see a shift in dialogue around the Soviet Union the most drastic during the most current period.

However, the larger issue is that while I laid out the history of thinking towards the Soviet Union, some of these cadres are not very clear cut. The Cold War Warriors and the Revisionists were often writing at the same time, and some of them wrote books even after the fall of the Soviet Union in 1991. Most of the Cold War Warrior generation is now deceased, and the Revisionists are all slowly retiring right now. Sheila Fitzpatrick and Stephen F. Cohen is now not teaching and are emeritus Professors. Most current historians fall into the latter two categories. Often though some may be trained under different professors or have different viewpoints that may align to an older cadre. I often described, for example, Anne Applebaum as the new Robert Conquest. She basically just rewrote his book. Something I stand by. You also have historians like Timothy Snyder who falls into the idea of totalitarianism for both fascism and the Soviet Union with Bloodlands. While Stephen Kotkin is definitely challenging the idea hard with his recent tomes on Stalin. Both books are within a few years of each other, and both are still predominate in the Soviet history space.

As an aside, I personally have major issues with the totalitarian model. It may be apt to describe certain sections, but it also is a form of erasure of history to me. Many people during the Soviet Union truly did believe they were building a better world. Millions did. Millions lived and died underneath that banner even with the idea of "Everything was Forever, Until it Was No More." It alleviates the culpability of those who did enact terrible harm to their fellow citizens and humans underneath Stalinism and beyond. It was not just Stalin, he is culpable to a large degree, but to everyone down who was "dizzy with success" as well. People believed in the system, for good and for ill and to ignore that because of a strong man theory, is to provide a reductionist version of history and something that is often even used to this day.

Adding a few words to /u/Soviet_Ghosts's answer, the term itself has not really fallen out of favor with historians of fascism, and it's unlikely to do so, given its extensive use in Fascist Italy to describe the social, cultural and political project pursued by the fascist leadership during the 1930s. That is - and I am more or less adopting the definition provided by Emilio Gentile in the 1990s - the organization of the "Totalitarian State". A state "organically" identified with the Nation, that is with the active collective of the producers and of their organizations, where every individual and collective manifestation, public or private, should find its proper place within Fascism, and never outside of it; a state, furthermore, organized around the figure of a "charismatic leader", whose leadership expresses itself through the structures of one party, perfectly integrated within the "natural" forms of organization of society (family, business, leisure, education); a state, last, which pursued this degree of absolute integration through an articulate system which paired the repressive instruments of a police state and the traditional forms of propaganda with a novel form of "political religion", of symbols, myths and rituals meant to facilitate the "integration" of the individual, and the "experience" of this idealized community and to provide them with a "meaning" and with a "representation" of that "palingenesis" which the Fascist Regime was, eventually, meant to produce.

Of course, the use of the term doesn't necessarily imply "consensus" on its meaning. In the 1950s, when even "orthodox" Marxist historiography was somewhat fond of it (in Italy, that is), the assumed meaning was close enough to that of a "reactionary authoritarian adopting novel modes of mass-mobilization".

It's also in the 1950s that - in no little measure due to the prominence of the Cold War to contemporary political and cultural discourse - the use of the term "totalitarian" expands significantly and earns a more "ontological" character, beginning to be used (in substance by "liberal" historians) in order to underline not only the respective similarities between the "fascist" regimes (and especially the most "complete" totalitarian one - National Socialist Germany) and Stalin's dictatorship (and, to a lesser degree, post-Stalinist USSR), which would give the term a mainly "descriptive" and, to a degree, perfectly legitimate character; but in order to stress an assumed "essential" connection between the two political formations. That, in other words, Fascism and Communism should, and could only, be examined and understood together.

In this, much stronger, sense (as used, for instance, by "totalitarian" historians from Talmon to Furet), "totalitarianism" doesn't appear to be regarded any longer as a particularly "fruitful" category. Even those, like Gentile, who investigate the "totalitarian" traits of Italian Fascism, tend to do so under the specific perspective of "political religions", and therefore adopting the traditional distinction between "democratic" and "totalitarian" as a mean to distinguish myths and symbols adopted, for instance, in the US, from those employed in Fascist Italy (or to draw parallels between them). Since Gentile regards the formation of such "political religions" as one of the central phenomenons of the XX Century, the fact that both Fascism and "Stalinism" gave rise to one, doesn't lead to assume an "essential" nexus between the two phenomenons. Rather, in some regards, the fact that the two pursued alternative forms of "palingenesis" calls more attention to their differences.

Furthermore, given its "Cold War" legacy, the term "totalitarian" is generally held as quite suspect in the field of contemporary Marxist historiography of fascism - especially in consideration of its not infrequent adoption outside of scholarly debates, and of its (negative) "revisionist" connotations.

In this context, the choice to use the term or not is less a direct consequence of the acceptance of a "totalitarian model", and must be understood in relation to the various particular debates which (re)opened during the late 1980s and early 1990s. The fact that the term should not - as noted by Juan Linz, for instance - lead one to erase the many differences between the two social and political phenomenons, is not in itself a guarantee that it won't, and its adoption remains, in some way, a legitimate object of controversy, as an equally (or more) productive comparative analysis doesn't appear to necessitate it; even if, as I said, it is certainly pertinent to an examination of Italian Fascism and, in all likelihood, to one of "generic fascism".

Gentile, E. - The Sacralization of Politics in Fascist Italy

Gentile, E. - Il mito dello Stato nuovo dall'antigiolittismo al fascismo

Gentile, E. - Le religioni della politica. Fra democrazie e totalitarismi

Gentile, E. - Fascismo di pietra

Gentile, E. - Mussolini contro Lenin

Gentile, E. - La Grande Italia. Ascesa e declino del mito della nazione nel ventesimo secolo

Gentile, E. - Le origini dell'ideologia fascista (1918-1925)

Griffin, R. - Modernism and Fascism: The Sense of a Beginning under Mussolini and Hitler

Linz, J. - Totalitarian and Authoritarian Regimes

Roberts, D. - The Totalitarian Experiment in Twentieth-Century Europe