Communism lacks understanding of the human nature. It fails to recognize that humans are sometimes apathetic, vile and corrupt. Darwin's theory does not apply only to evolution pre homo sapiens. It manifests in all of nature. Communism refutes that theory at it's very core and removes the mechanism society rewards individuals for following their instinct. In fact, it punishes them for it.

Communism/socialsm has noble ideas. But those ideas live in a silo. When they touch reality everything shatters.