The problem is, with a broader historical lens, Communism is a system that typically gets adopted in countries that have had a history of oppressive feudalism. Like it or not, the average Russian's lifespan and standard of living _improved_ under the Soviet Union, and the same is true if you compare the China of the 1920s with today's China. Look, Ma, no footbinding! No slavery!
The reason why those countries adopted Communism as a system of government are THE SAME as why it came with atrocities.
