The problem with communism is that it can never be properly applied, and more importantly, maintained. The most basic principle of communism is that all are given equal access to resources, which are gained through equal effort.
The issue arises of leadership. With any population over 20 or so, a direct democracy is not suitable for all minor decisions. Imagine the inconvenience of gathering a huge population just to decide if the logs should be brought up the east or west side of the mountain. Centralized decision-making is quick and efficient.
A leader must be assigned to distribute tasks and resources more effectively - but as scholar Lord Acton simply puts it, “Power corrupts.” No leader is completely free of selfishness, prejudice, and bias. There will be inequalities in workload and reward - and just like that, you’re back to having a proletariat.