Controversial content breeds engagement, which is, I would say, one of the most important metrics companies like Meta, Google, or Twitter (sorry, X) rely on.
X would allow a literal nazi posting freely on their site, with the occasional post deletion, as long as it generates impressions. They could remove the content, they choose not to.
It also breeds censorship. I'm allowed to watch a 15-minute long video about Steve-O's experience with PCP, but can't post a picture of my cannabis nug that I just bought (Got an account warning for 15 days because of this). I also got suspended for 15 days for posting a meme I found on Facebook itself.
This is why I'm considering switching to Tumblr for stuff like this. Although Tumblr censored a bunch of NSFW recently, and that's a slippery slope. I'm certain they can ban other types of content just for being slightly controversial.