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).
Read up on rhetoric, hard sales tactics and CIA/KGB sabotage. Here's a fun little one from the OSS that's still used in 2020:
(8) If possible, join or help organize a group for presenting employee problems to the management. See that the procedures adopted are as inconvenient as possible for the management, involving the presence of a large number of employees at each presentation, entailing more than one meeting for each grievance, bringing up problems which are largely imaginary, and so on.
I wonder if there are resources on creating divisions. It's a very interesting social science topic.