Why do we not excoriate Stalin's and Mao's latter-day followers (communists, socialists) and label them with their fathers' genocides as we do with Hitler's?
Because we're unthinkingly fashion-led, that's why.

What an Idiot!!!! Stalin was no more communist than Hitler. Both were dictators you fool. And as for Mao being socialist - well thanks for that one, I've not had such a good laugh in ages. Dictators the lot.
John Barden