(Warning. A mild rant follows. Not suitable for people who don't like re-evaluating things)
I get lots of inquiries from people asking me to follow them on Facebook. Inevitably, if I respond at all it's to say that I don't do Facebook. I tried it once and found the noise level horrific and overwhelming. Little on "my" page had anything to do with me.
And most things didn't actually seem to be ON Facebook anyway but, as with twitter, links to thing somewhere else. Facebook was just the medium for sending me where the person wanted me in the first place. All the political rants that seem to assume I agree with them anyway were nauseating (often worst when I did agree with them). Pictures of people I don't know eating food were not entertaining. (Pictures of food? Give me a break.)
The thing is, life's too short for that nonsense. It was nice to be able to communicate with people, when it worked, but I couldn't be sure people saw my messages unless they specifically answered, and for that, I have email which is nicer, more "me friendly" as it were. Most important, other than going through myriad servers, it is just a communication between myself and another person, one not categorized as a "Facebook Friend"--a strange marketing label if ever there were one.
Very quickly my enthusiasm for checking my Facebook page waned, and shortly after, I deleted it. That was about eight or nine years ago. I don't honestly think I've missed out on anything important in doing that (but how would I know, right?) but I do know it gives me more time, and time is a precious commodity.
Every day it seems that my "friends" on other sites invite me to join them on "the new Facebook"--something I believe the world needs about as much as it needs another Enron. I don't reply. I don't join. It isn't that I am not interested in what other people are doing, but I figure if you want me to know, there are a lot of ways to send me a message about it, and the point of all going to some site every day is rather lost on me. I'd prefer to hear from you in a unique way. I have one or two friends who call me on the phone. What a concept!
I do participate in a few online things that I consider marginal, but only because they are nearly automatic (take zero time from me) and I view them as relatively harmless. Increasingly this chaotic world makes me seek out the relatively harmless (in the wrong hands, nothing is entirely harmless).
If you love Facebook, if it works for you and what you need, I'm glad. It must work for a lot of people or they wouldn't bother (I hope they wouldn't). But I won't be there, and it isn't because I'm not your friend, or don't like you, but because I don't see it as a substitute for whatever it aims to substitute for. The truth is that there is not a global online community. There are online interactions, but not a community. And sticking "global" and "community" together as a single term... well, think about it for a while. If it still makes sense to you, then fine.