You know, I thought the same thing. But honestly I rarely used those forums. And the people I can't keep in contact with, well... I don't really miss them. I have phone numbers for the people that matter and have resumed exchanging phone numbers with people, which I hadn't really done in several years.

I am part of an organization that uses fb as the primary means of communication. The people that at the top have been pretty obnoxious about me not being on it anymore. But frankly, I see their attitude as pretty toxic and think they should move to a professional method of communication (they are a pretty amateurish / small org).

Sometimes disruption is a good thing. I've been studying a lot more (as a professional dev taking online classes) in the past few months since leaving fb.