Because white supremacy is the simple belief that ones white skin makes you superior. But the Nazi belief system transcended even that, the Nazi's put stock in ancient bloodlines with cult like religious zeal, there actions against other whites both Jewish and Slavic is a clear display of how their belief system wasn't just against other skin colours, but against anyone who didn't fit into the specific Nazi ideal. I think you're minimising the overwhelming hatred the Nazis had for almost everyone when you simply label it as white supremacy.
By labelling it was white supremacy, many people on this continent have fooled themselves into believing the Nazi's were on their side. They werent.
Yeah, I have a clear track record of personal attack