The latest, and longest lasting, defense of communism is that it’s mismanaged (earlier defenses put it as “not done right, not implemented right.”
Stipulate that a problem with communism (and each of its socialist variants—socialism, fascism, social democracy, etc) is that it’s mismanaged.
That no communism or socialist variation has ever succeeded in all of human history is a clear demonstration that nations, or economies, cannot be managed successfully from the center. It’s just too hard, nations and economies are too complex to be…managed…from the center.