Hitler and Nazi's were literal pikers compared to the evil and poison of Karl Mark and Engels philosophy. Communism is the worst thing to happen in the history of civilization- Muslim/Islam is a distant second.
It's funny that Marx's philosophies have led to death and destruction everywhere it was allowed to ferment, Lenin, Stalin, and Mao using in part Marx's theories led to the deaths of 100's of millions of people, yet Hitler is Voldermort. And somehow worse than all of them combined. Makes sense.
You are suggesting that somehow they're thinking is unique. It's common. They just happened to put pen to paper and get historical credit.