Facebook added nothing to my life - indeed it actually harmed some relationships since I figured people didn't need to communicate directly with me if they could follow my public feed.
Twitter became a vector for me to bitch about the world to no one in particular. Try as I might, I usually ended up sending out a stream of negativity which the world certainly does not need more of and it does nothing good for me personally.
I'm considering ditching LinkedIn, but that seems to be taboo - HR drones seem to expect a LinkedIn profile and get suspicious if there isn't one (this isn't a good trend IMO).
Since terminating many of the "social" media services in my life, I've felt better about how I present myself to the world. I no longer fret about that last tweet I sent out, or feel a need to check on my "feeds". That said, it does leave me looking at my smart phone and wondering what the hell to do with it.
a) this isn't true.
b) The whole HR drones thing is pretty lame. "Hey I assume I'm way smarter than everyone in this field because I said so".