Why do Progressives never have a bad word to say about Communism or mankind's most prolific mass murders, all Communists?
Because communism has never killed anyone.
Stalin was not a communist, but a capitalist bank robber, who infiltrated the Communists, Socialists, and Anarchists, killed them all, took over, and implemented state capitalism instead.
Look at the characteristics. Communism is collaborative, cooperative, communal, and the way humans normally treat each other in small social groups like families, clubs, tribes, etc.
Those who think communism implies a large centralized state, simply do not know anything about communism.
And what Stalin implemented was not at all collaborative, cooperative, communal, or voluntary.
It was forced, state, capitalism, with purely a profit motive for the ruling elite.