Earlier quoted context omitted.
Spam killed forums. Facebook took since it wasn't plagued with spam.
Facebook content is now such low-quality that it might as well be spam (my opinion). Also, pointless, toxic conversations. It seems to bring out the worst in people. I know some people like it for keeping in touch. I refuse to use it anymore, not worth it for me.
The conversations on FB range from informative to toxic, and depend, like the internet forums of old, on the moderators. As FB does not actively moderate discussions, toxic conversations are the fault of the participants and the moderators, not on FB.