Accepting 1500 friends and then complaining they’re too many. Who’s to blame here?

Facebook is what you make of it. It offers relatively granular control over who you want to see so if even you must be friends with someone, you can still unfollow them.

Surely the default is a bit annoying, especially when joining groups, but those can be unfollowed too.

The only thing I can complain about is “your friend reacted to or commented on some post” I don’t care about. That’s Facebook’s fault but your friends are your fault. Most of the time I add friends and promptly unfollow them because they share memes.