I've had Facebook for almost 3 years. Before that was MySpace and Bebo.
Didn't really use MySpace and Bebo much but after a while on Facebook, I was extremely active; literally posting a status everyday.
However, now I barely post anything at all. I stopped using Facebook by getting someone to change my password a month or two before the end of year exams but after exams, I no longer post anything. Even before giving my password away, most of 2011 I didn't really post anything on facebook besides changing my dp every now and then. It's as if I'm scared that I'll get judged. I do still comment and like other people's status occasionally but I never actually post one myself. Neither do I post on other people's walls unless it's someone I've just met and I want to talk to them.
However when I look back at my timeline at all my past statuses, some of them are actually decent and get a few likes and comments. Not sure how I was so confident when I was younger but I guess as we mature, we're scared that we are going to get judged so we become more reserved and privacy becomes more important to us.
Also I actually never use Facebook to talk to my close friends. Honestly I hate Facebook chat and would much rather use MSN or Whatsapp. It's sometimes strange when the 'View Friendship' page of someone I just met is more filled than the 'View Friendship' page of one of my closest friends.
With respect to the OP's article, another factor why Facebook makes us miserable is Notifications. I have a sister and she's actually sad if she hasn't been on FB for a while and when she does log back in, she only had 5 notifications when she was expecting like 20+. I kind of understand her except with my case, I'm miserable because I expect one notification but actually have zero....
Regardless, Facebook isn't all that bad. It's actually pretty amazing and allows us to keep track of what's happening in all our friend's lives.
Knowledge is Power. But too much knowledge can make us miserable. Sometimes we are happier just not knowing anything...