If it's not state-run (or otherwise mandated), I think you'll still see significantly unequal access to friends (and family members) of different attitudes and aptitudes.

The really interesting thing about Kibbutzes is that they're radically communal - to the point where children are not supposed to belong to any individual, but to the community.

I'm sure it's impossible to factor out the human element of relationships, but it is interesting to me as an example of the spectrum that human societies will build.