Communism is not the same as socialism. Communism is collective ownership with no state, while socialism is state ownership supposedly on behalf of the collective. Socialism is a hack used to approximate communism because real communism is an entirely incoherent idea. That's why most examples of supposed communism are actually socialism.

Communism means collective ownership, and ownership defines who has the exclusive right to control how a scarce resource is used. Everyone can't exclusively use the same scarce resources. That's what "scarcity" and "exclusivity" mean. Because of this, claims of collective ownership require the creation of a single entity trusted to speak on behalf of the collective. This is typically the socialist state.

Communism could only appear to function if the collective were entirely homogeneous and all its members shared the same preferences such that there was no conflict between them. Given such an absence of conflict, it would not matter who was recognized as owning anything so communism would offer no benefit over alternatives.