counter question: was Nazi Germany totalitarian? You had nazi existentialism, nazi protestantism, nazi catholicism, nazi biologism, nazi positivism, nazi idealism, nazi this, nazi that. They didn't purge everyone who was did not subscribe to a particular doctrine like they did in USSR. They had no frills with Nietzsche, Kant and Martin Luther. Instead they emphasized their sides which they liked. There was no nazi Stalinism, there was no single nazi ideology. The book of Rosenberg is oftentimes quoted as such but it was never read by Goebbels or Hitler and it's views have never been enforced. With Rosenberg you could be a nazi atheist. With Emmanuel Hirsch you could be a nazi protestant. With Hanns Frank you could be a nazi Kantian. With Jörg Lanz von Liebenfels you could be a nazi catholic. Basically you could be anything as long as it did sound remotely nazi. Hitler only read the latter. In Stalinist USSR (and, supposedly, in Maoist China which I know nothing about) everybody read the canonical works of Marx, Engels, Lenin and everybody was required to conform to the latest party line, speaking of everything through the Stalinist lens.

Of course, if you take this definition of Totalitarianism then Moussolini wasn't so totalitarian either. And it was him who coined the term. But in post-war thought, such as that of Hannah Arendt, this term was used to group Nazi Germany together with the USSR, much like the USSR used "imperialism" to do the same thing with Nazi Germany and France and England and the USA. The nucleus presumption is "Totalitarianism when one ideology is enforced on everyone". But in the fascist countries there never was one single ideology comparable to those of Leninist one party state. You had some vague chauvinist bullet points that were ought to be respected and some ideologies, such as Marxism or Psychoanalysis, were declared heretical but otherwise you could be anything.