Because communism tried to equalize people by taking everything they owned and made state property from that, while they detached the state from the society and organized it feudalistic style where every official was bound to it's superior in a fidelity chain up to the top dogs who ruled as kings. Those benefited of the system who were loyal to their overlords in this state, whom shared a small portion of the fruits of work of the oppressed laborers with their vassals.
While in real feudalism achievement and talent meant a good way of rising in prominence, here only loyalty mattered, and even common sense was sacrificed on the altar of power hungry jealousy and dogmatic handling of the ideology. This made the the work of the state machine inefficient and squandered the strength and the potential genius of the enslaved masses.
im yet to see a person who's like communism and isn't a brainlet (only exception being finnish commies who are good for mysterious reason)
because it stole from the people to give to the (((few)))