The problem is, despite all of the slop and garbage and surveillance and everything, Facebook is still actually valuable for many people.
People use it to keep in contact with relatives and friends, I follow work groups, my mother took COPD therapy through Facebook and chatted with relatives in other countries. I think Hacker News has been so radicalized against social media and "algorithms" that they forget most people's relationship with social media is entirely mundane.
He was always like this and never intended to create something actually valuable.