Ordinary selection pressure and the 'development of progressive genetic traits' spearhead evolutionary survival and continuation as a species. At some point over-population and competition for resources can cause an extinction event. Ask any lemming. 
I am not contesting the Holocaust, but rather commenting on 'positives' in the result - which is as difficult to rationalise for many, Jews in particular, as it is for those who suffered under SA colonialism to have the benefits of colonialism extolled by those who really did benefit. I completely agree with your last line - the Holocaust remains to be a horrific genocide of the Jewish people.