>Once it gets too big for that, you're doomed to destruction eventually.
>My preferred solution would be to break up the communities once they're too big, instead of trying to make a massive world-wide community like Twitter does.
I agree with this. In real life situations you can see it too, the larger the crowd the stupider their total behaviour becomes. Large crowds are good for certain things though, but mostly primal stuff like singing and chanting.
Once it gets too big for that, you're doomed to destruction eventually.
My preferred solution would be to break up the communities once they're too big, instead of trying to make a massive world-wide community like Twitter does. Reddit somewhat has this, but there is still a site-wide issue.