Well, take me. I joined facebook two years ago after avoiding it for years not (just) because of the reasons you mentioned but also because i was very privacy focused.
The only thing i found out, after connecting with a few people i know around me and scrolling through their history on facebook...the big party is over and i am too late.
Facebook isn't what it was anymore and people don't use it that much to connect with others.
Excluding, let’s be honest, a couple of weirdos who don’t use FB as ideological stance is a problem.
Excluding huge swaths of “normies”(who are majority of people) by setting up third party website with zero reputation is not.