I have been thinking of something like this. Nevertheless, steem is already compartmentalized into communities. Maybe not as local as you suggest but then, it further proves that your idea will work in execution because all this communities are working on a not-so-micro level.

Most communities that exist are national, there are some town communities but the national ones have strength. That is just geographical, interests-wise, there isn't so much of that.

I see utopian as an interest-based community same as some other unmentioned communities , what I am just saying is that your idea is not new but that is further proof that it will work because it has been tested and it is working.