The article is pretty light on how these platforms do so.

Do they not simply bubble up popular posts: ones with likes, retweets, and comments? That might mean a politicized post, but it also could be a positive one about the kindness of a stranger or some cute picture of your kids.

These platforms may well be incentivizing enraging posts. I just don't know how they're doing it, and this article did not help me understand it.