1. Rabbonim have a selection bias – they only hear about the problems. Nobody goes to them to tell them that they use Facebook to keep in touch with their relatives in EY.
2. As with most discussions on YWNCF, if it’s not black and white people ignore it. Also, people make up stories so they can have black and white reasons to be machmir on things. Not about Facebook specifically, but my extended family, who live in various places, use the internet to share details about our daily lives, mail baby pictures, purim pictures, wedding details to relatives who couldn’t make it, etc. Who’s to say that Hashem doesn’t want that? Why should I forgo that because R’ Aviner claims to know dozens of people (whom nobody else has ever met, and whose experience no sane person could replicate) who are “addicted to” and “got divorced because of” the internet?
Claiming that Facebook is terrible is not only ridiculous on its face (lol) it diminishes other messages that might actually be worth spreading.