[disgruntledphd2]

I guess so, but it's not really an interesting question because it's so easy.

Humans are (somewhat) pre-disposed to form in-groups and out-groups, and clearly those people are worse than us.

The only real difference between pre-internet and post-internet is that it's much, much easier for fringe ideas to spread (and often this is good, like gay rights were a fringe idea twenty years ago).

However, we don't get only the good (for whatever your definition of good is) stuff, we also get people who particular in-groups don't like organising, and this sucks. But everyone's out-group is someone else's in-group, so unless you can solve humanity, you're not going to fix Facebook.

To be fair though, I trace the divisions in American society mostly from the decline of the Fairness Doctrine, and all the downstream consequences of that (specific channels for particular worldviews leading to increased radicalisation).