Partially, this is because of the way that Holocaust survivors tended towards telling their stories in the immediate aftermath of the war, and it is also due to larger trends in historical practice from the 1960s-1990s.

By the time of the Holocaust the historical value of oral history was already understood. During the 1930s the American government for example created a program through the WPA where workers would contact people who were formerly enslaved and record their oral histories. This was done because it was known that the people who were born into slavery were becoming very elderly, and as a significant portion of formerly enslaved people were impoverished, and some were not fully literate, they would not have been able to formally publish their autobiographies.

During the Holocaust many Jews felt a need to record their personal experiences often because they hoped something of them would survive even if they did not. This was even part of the motivation for Anne Frank when writing her diary. Thousands of other Jews kept diaries or wrote letters or created art which was meant to represent their experiences. In the Warsaw Ghetto historian Emanuel Ringelbaum helped gather together the writings, diaries, documents, and art of hundreds of Warsaw ghetto inmates in milk cans. Most of these people did not survive, but two of the stashes of documents were saved, and this allowed these people's stories to be told.

After the Holocaust, survivors tended towards first person narratives, even if they were creating synthesized narratives. Various groups, many connected to the Central Committee of Polish Jews, collected survivor testimonies as part of gathering evidence of the crimes of the Holocaust. DP camp officials and aide organizations also gathered testimonies, both in an effort to document what the Nazis did, and sometimes to reunite families or even attempt to prosecute war criminals.

Survivors from various communities gathered together in DP camps, in their new homes in the US, Israel, and even Argentina to create Yizkor (memorial) books which gathered together the histories of their communities, from their creation through to their destructions. These books were written in many languages, and were written from right after the war to around the 1980s, most are viewable, and some even are translated to English through a resource called JewishGen. The Yizkor books combined oral and written histories of the town, folktales, stories of local personalities, necrologies of victims, photographs, oral histories of the Holocaust, documents, and other information about the town so that the memory could be preserved even when there were no Jews left in the villiage.

Over the next few years some survivors, particularly those who had been academics, writers, or had secondary education before the war began to publish memoirs of their Holocaust experiences. One particularly damning example of a survivor memoir is Dr. Gisella Perl's horrifying and haunting memoir I Was a Doctor in Auschwitz which she published in 1948. In As child survivors grew up, they too began to write their own memoirs, one of which was Night written by child survivor Elie Wiesel during his early adulthood.

The 1961 trial of Adolf Eichmann in Jerusalem showed the world the power of survivor testimony when the prosecution team decided to spend a great deal of the trial calling witnesses, many of whom had never seen Eichmann personally, but who had experienced the horrors his orders created. Hundreds of thousands of survivors saw their stories broadcast and taken seriously on international television. They also saw their stories used to convict one of the most important architects of their suffering. This spurred many to start talking and writing about their experiences once again.

From the late 1960s through the 1980s the field of history was also changing. The old way of writing about history which often focused on major events and famous players rather than the personal stories of everyday people was beginning to be replaced by historians who saw significant value in the oral histories of normal people. These historians began to understand that the experiences of normal people could tell us as much about history as documents by generals and the like.

One of the first historians to start applying this focus on collecting oral histories to Holocaust survivors was Professor Yaffa Eliach, who was herself a child survivor. When she was teaching Holocaust history in Brooklyn in the late 1960s she realized that not only herself but many of her students were Holocaust survivors or the children of survivors and each had a unique story to tell which complicated, expanded and diversified the collective knowledge about the Holocaust. She began to interview her students, and ask her students who were children of survivors to interview their parents. I myself have actually gotten to translate some of these early interviews and they are absolutely incredible. She and other scholars began to create standard ways of performing interviews, sets of questions, and other ways to standardize and expand the collection of survivor testimonies.

Throughout the 1970s and into the 1990s new initiatives through museums, foundations, and universities began to be created to try and interview every survivor so that their stories would never be lost. Steven Spielberg spent a great deal of the revenue from Schindler's List on the USC Shoah Foundation which hosts tens of thousands of interviews, Yad Vashem, the USHMM, the Yiddish Book Center, the Fortnuff Video Archive and many others have made sure that survivor's stories are not forgotten.

The Nazis attempted to dehumanize their victims. To strip them of everything, their homes, their possessions, their families, their hair, their names, their stories, and eventually their lives. To focus on the old ways of writing history which focused, for example, on the Nazis own records tend to disregard the normal people who lived and died through history. Survivor testimony can be used to create synthesized narratives, and often are, but their historical value as the record of an individual experience is just as important. Holocaust history is often done at the intersection of memorialization and recording history. Each testimony is a memorialization of all those in the survivor's life who did not survive, and a memorialization of the horror they went through themselves. It is also a way to hold the perpetrators culpable, by documenting how normal people became murderers. Testimony also re-centers the experiences of the victims and survivors, and reminds us that history is not made by "great men" but by each and every one of us.

https://www.yadvashem.org/education/educational-materials/learning-environment/use-of-testimony.html

https://mjhnyc.org/blog/testimony-and-remembrance-deborah-dwork-at-the-third-annual-dr-yaffa-eliach-lecture/ (This is my own publication)