I disagree with your take -I don't see it being a question of moderation. You had many of those groups online (if not all of them) in the 90's and 00's. Unlike today, if you didn't like the forum you were on you could go to another one where you fit in.

There was a greater diversity of social gathering places.

Now -there's facebook, twitter, reddit and HN.

Moderation has ALWAYS been a factor and that's not what made the old internet better.

What made the old internet better was that it was open and more diverse (in terms of viewpoint and choices). The new internet is basically (on a social level) a few social media corporations which are becoming increasingly sterile.