You give a small group of people monopolistic authority over law, defense, arbitration, and the allocation of all property, and instruct that group of people to make everyone equal.
(Naturally, since this is a state we are talking about, there are virtually no repercussions if they pursue a different course)
That small group of people, as selfish and self interested as the rest of humanity, does the rational thing and rapes the wealth for their own benefit, and essentially equates communism with feudalism.
Communism is Utopian for placing all that power in the hands of a few, and expecting good things to come from it.