Mao didn’t have to lead a mass of Hitlers! They had come off the Taiping Rebellion and the Boxer Rebellion relatively recently before the start of the civil war, and most crucially, Chinese workers and peasants were at the bottom, not top, of the global labor pyramid. Chaos was to their benefit.

edit: not to mention that class collaboration helps a proletarian anticolonial movement like the Communists in the Chinese Civil War because it aligns elements in the national bourgeoisie and proletariat/peasantry against the colonial ruling class; the nature of a similar conflict in the US would surely have it reversed where white workers would collaborate with the ruling class to protect their place (this is literally already the precedent for the American Revolution and the Civil War)