Left years ago...
I recall joining Facebook to keep up with family, most my friends were on other social networks.
It was fun for about 5 minutes, until I kept getting pestered.
People came out of the woodwork, some I'd had no contact with for 20 years. "Hey, remember at school when?" "Erm, no, I've moved on, forgot that."
The main 'social' aspect seemed to be data gathering games "Will you allow this application to grab all your Facebook details in order to demonstrate to friends how clever you are?" "Erm, no. My friends don't care about that crap."
But some of them did, "Friend X scored 1200 points in 'cool game Y', can you beat them?"
"Erm no, Friend X just gave away all their personal details to a marketing company."
It's crock, it's been crock for years.
I guess, like a true alpha geek, I'm just an unsocial bastard who prefers a small group of friends and chatting face to face. I'm a sucker for Twitter, because I follow people who provide humour & good links. Google+ - yeah, got on it months back, posted my usual pile of silly jokey crud and funny photo's, got bored with it.
The reality is, the social web is what you make it, not what a website *wants* you to make it.
Facebook is a marketing tool masquerading as a friend hangout. Google+ is a wannabe Facebook designed to peddle Google's ad network - and gather personal data.