You could be fully into communism and think genocide is a stellar way to advance your goals
Not really. Communism is stateless, and I just can't see genocide being possible without a state apparatus to back it up. When power is truly in the hands of the people, the people have a moral compass that tells them no to such atrocities. The fact that responsibility was/is so concentrated in the hands of evil men that they could perpetrate genocides is part of why China and the USSR are/were not communist. State socialist at best, state capitalist at worst, and also probably most accurate.
Lenin [...] were very very left
Valid point.
Stalin were very very left
Lies.