In the theory that is communism, people are not allowed to partake in consumption unless they are active in production.
As you say....in theory. Human nature gets in the way though.
My grandmother was an idealist who embraced the idea of communism at some point in her life. She got over it. I suspect she realized that she wouldn't be able farm out her kids and spend every summer vacationing and visiting her family in Brittany, France if she really was a Communist. She also gave up Catholicism for a number of years, instead embracing the teachings of Mary Baker Eddy, but she returned to the fold before she died.