People that are calling it a failure because of quality are missing the point.

Facebook makes its money by leaving the feed an unorganized mess of random posts, leaving the user disoriented so that more eyeball time can be harvested for advertisements while the user searches for the content they want (or gets stuck mindlessly scrolling the infinite reel of videos and other content for that dopamine hit).

It's not lost on the army of six figure salaried engineers that a lot could be done easily to make the experience better. But that isn't in the interest of the shareholders. The quality is a feature, not a bug.

It's used regularly by over 1/3 of the human population. I think that by itself tells you it's an useful product. It might have some flaws (as do many other products), but it seems the vast majority of users overlook those flaws. I'm definitely not a regular FB user, and even hate it, but I can't deny many many people find it useful in their daily lives, flaws and all.