Also, while Mein Kampf described many races as inferior, the actual mechanics of what would be the Holocaust and the decisions that resulted in the Final Solution were largely shaped over time through small decisions that fed on each other by multiple individuals.

Put differently, Hitler never ordered the Holocaust directly or personally. Yes, he talked a lot about the end if the Jewish race, but to pretend he was solely responsible for coming up with this policy lets the other architects of the Holocaust off the hook way too lightly.

None of that excuses him and his regime overseeing and directing these atrocities though. I think we can all agree that this was a uniquely evil policy for which there is no punishment big or fitting enough (even the Nuremberg trials struggled to (and acknowledged) mete out judgement that was in any way proportional to the suffering the defendants had caused).