Your examples show (at most : but not really that) the Holocaust did happen, not that it had to happen. I suspect you mean that it certainly did happen. This I accept as plain historical truth. If the Holocaust didn't happen, then it's incredible that there should be so much evidence that it did happen. Yet, just to dwell on one point, the Diary of Anne Frank seems to me a flawed and faked document in the sense that it has been heavily edited. The story of Anne Frank is a terrible tragedy; I have cried over her death. But I do not believe that the diary, as we have it, is her own work entirely. Whatever her experiences, the diary is simply too adult in its tone and insights to have been the untampered work of a teenage girl. I suspect her father edited it significantly. The tragedy of Anne Frank is not lessened in any way by this. The persecution of Anne Frank was a crime against humanity, no more and no less.
because it did happen! I dont understand why this question is here truthfully
Almost no one denies that it happened entirely, Holocaust deniers, deny that it happened to the extent to which it is remembered. For example, the number of people dead due to the Holocaust is one of the main arguments against it, also, it is important to consider, why is there so much attention being paid to one group of all the people who suffered because it? This is important when you consider how many other Holocaust-like events have happened in history, including recent history.