As someone who's just recently read The Dispossessed, I would be remiss if I did not correct your characterization of it. The lunar society in that book is quite clearly anarcho-syndicalist. Much of the conflict early in the story stems from the syndicate structure of that society.
This should not be confused with Soviet-style centrally planned, state-capitalist, 'Communism' if that's what your acquaintances called it. It should also not be confused with actual communism, i.e. a classless, moneyless, stateless social order.
>Capitalism is inevitable.
Spoken like a true capitalist. Fukuyama would be so proud.
>the farms and kibbutzim themselves are still participants in a larger capitalist system
If the revolutionaries had their way, they wouldn't have to be.