Friends who say “Why aren’t you on FB?” invariably say within a few sentences, “You have to wade through loads of shit to find what you want”
User error.
It requires a degree of maintenance and quality control. If you “friend” everyone you’ve ever heard of ever then it can get out of hand pretty quickly. If you’re friends with people you’re actually interested in hearing from and spend a couple of minutes selecting the options to hide posts from groups / topics you have no interest in, the wheat to chaff ratio improves significantly.