I think that the reason that our classic image of the Holocaust is Auschwitz in 1944 is that there are a lot more survivors and witnesses of that late period of the war than there are of the massacres carried out by the Einsatzgruppen in 1941 or 1942 or the earlier Operation Reinhard death camps, which left almost no survivors.
A year or so more of war and the Holocaust would have “never happened”.
Ever read “Fatherland”?