Cons of the Communism society:
Contrary to popular belief , the " survival Of the fittest" is not on Capitalism, its on Communism.
Money is often used to hide lack of intelligence, creativity or just pshysical or mental qualities..
In the Communism society from above, the talent will be rewarded not with money but with visible "titles" or "rewards" to continúe the human progression, those rewards will worth more than actual money because today money can be gotten from many sources not only "success", it can be given even for free.
So with this rewards, the people that is just "stupid" or below average will be more visible, stupid people could expect some kind of social bullyng or exclusión from various activities.
We have tried something like this but it didn't work. Humans by nature want more, and better stuff. (Stuff can be literally anything from knowledge to money.) You can call it greed if you want. If you suppress this kind of greed then you will get only stagnation. I've seen it in the last decade of socialism, ppl wasn't motivated at all, everybody thought why do anything above the acceptable minimum if they can't get anything more or better just stupid titles and worthless badges. Finally this lack of motivation paralysed the whole society what collapsed pretty soon.