Marx was wrong that somehow continued could bring about a fairytale utopia where everyone has abundance just because because no one is profiting from their labor. Communism doesn't work because there is no mechanism for marshalling resources to devote to solving problems or increasing productivity other than the state, but in a state where there is supposedly abundance, there should be no need and the state has no reason to about there is. Development stops because it is antithetical to the communist idea.
In reality, it is the utilization of pooled resources, brought about by some entrepreneurial individual, that enables increased efficiency in productivity and the creation of value. It is not enough to merely own the means of production. They must be organized, arranged, and directed to productive means, and the typical laborer is incapable of that. So if the state. Giving people the freedom to resources and to trade and borrow allows those best capable of creating solutions to apply themselves to problems. They may get rich, but everyone wins because increases in protectivity mean less goes into producing more, creating abundance.