Communism is incoherent.
It can’t work in the real world – it is not nearly detailed enough to explain how it can, should, or ought to work.
It only seems reasonable if you describe it vaguely. If you try to answer the details of how it would be administered it quickly falls apart.
People like to claim attempts at communism have not been ‘real communism’ – when in fact there is no such thing as real communism when applied to the real world.