Stoller: These [intentional] communities are able to operate with few rules---and little open authority---BECAUSE they have rejected potential members who would clash hourly with the commonly held values of those who formed these voluntary associations. The more ideological harmony in advance, the less authority will be needed later on.
: I'm no sociologist or anthropologist, but I have a hunch that man is a tribal animal, with the tribe being no more than maybe several thousand strong, and that beyond that, you will always have inequality and brutality...
One problem: economics.
Although a several thousand-member community (Fourier, anyone?) will have less interpersonal friction (providing that ideological selection has occurred), it won't be able to produce very much.
A several thousand-member community will not be able to develop heavy industry, medicine, or enough surplus to sustain much leisure / culture.
Several thousand people will only be able to get some primitive agriculture up---unless they trade with either other communities (each producing a different necessity) or the capitalist world (which will undersell them every time and, thus, get more labor-power from them then they receive in return).
Also: such a small community would only be able to produce one or two commodities (such as hammocks and tofu!) and, therefore, job availability would be limited to only a handful of tasks (dull!).
Peasant or petty-proprietor communism, in my opinion, is the communism of scarcity and poverty. It may not pollute but, as Twin Oaks' long-term record of 70% member turnover demonstrates, does not satisfy, either.
Marxist communism is predicated upon industrial abundance---abundance great enough to satisfy material needs as well as provide variety in work ('spiritual' needs)---which is predicated upon socialized labor. It's a whole different thing and, in my opinion, a far better and more realistic thing.