You have to understand the theory behind the religion of Socialism/Communism/Democracy/Whatever The Current Re-Brand Is.

A Socialist society is one in which True Equity has been achieved. The State sort of just fades out of existence, as it is no longer needed to ensure cooperation.

This has never happened, because it will never happen, ergo cue the cries of "True Communism has never been tried!"

The fact that every attempt has made the Nazis look like a troop of Jainist Girl Scouts is immaterial. Slaughtering a hundred million people while redefining the depths of human misery is fine and dandy, as long the goals are noble. Can't make that omelette without breaking a few eggs.