But what if some of those small communities engage in no-no think? How can we allow those with no-no think to co-exist with our world? Shouldn't they be stamped out of existence for the good of everyone else who doesn't have no-no think?

Sadly the above is a very common belief structure now. It's a product of utopian thinking where if just this one more enemy can be destroyed, peace will fall upon the Earth and all will be well. It seems to be that these utopian dreamers always end in the elimination of those who don't share their dream vision of the world.

I would much rather go back to a series of small private communities with known members, much like how the physical world still has neighborhoods and groups of friends.

It still has plenty of idea sharing but enough social friction to support proper filtering and decorum.