From what I've seen, communism as a system only tends to work in highly select, homogenic, localized, low pop systems, such as the kibbutz in Israel. So you can't say it's never been tried. It has, it just only works in very small instances where everyone is on the same page and opts in. Applied to a broader region there are too many diverse skill sets and interests to square everyone into the same hole. Fact is, very few will choose to opt into a system in which they can't succeed and compete against their peers. That's human nature. Which is why communist system's always end up using force and violence.