Content that makes people angry and get into bile-filled back-and-forth screaming matches with each other is fucking amazing for engagement, so Facebook et al push it to the top of peoples' feeds in order to get them to keep clicking, and to keep serving them ads.
Maybe Facebook hasn't really changed since it began, and "maximising engagement" has always been their main priority. But it's probably a pretty safe bet that they've put a lot of effort into that, and got much, much better at it in the last 15 years.
From the article:
> In July, Nick Clegg, a former Deputy Prime Minister of the U.K. who is now a top flack at Facebook, published a piece on AdAge.com and on the company’s official blog titled “Facebook Does Not Benefit from Hate,” in which he wrote, “There is no incentive for us to do anything but remove it.”
I would disagree. I submit that hate drives engagement, engagement drives eyeballs on adverts, and eyeballs on adverts drives $$$$, which absolutely benefits Facebook, and gives them an incentive to keep hate on the platform.