Just wondering: why do people here tend to call Communism "evil" and "unfair", if its basic ideology is..?

..complete friendship, love and care without any coercion among society members, without this " homini lupus est", which actually is the basic of almost any other form of government? I agree that the recent realizations of Communism are/were quite ugly, but it's the fault of people who were establishing and running it, not of the idea itself. So why do people demonize the beautiful and wonderful idea they know nothing about, and actually have never seen truly realized?