Is it really about what they write, or about what they read? People were putting out information that all of the parties you mention could read long before Facebook existed. I still remember "NSA food" on Usenet. Those privacy concerns, while valid, have never become foremost in most people's thoughts, even among technorati.
Out there among the Great Unwashed, I suspect the issue is more about the value they get from reading. People read a lot more than they write, after all. People were already getting tired of watching all their friends' highlight reels. Then since the last election there have been far more fights in comments, and the feeling of being manipulated, and people pretty naturally start to wonder whether this is time well spent.
I'm not dismissing your concern, but I don't think it's particularly relevant to the OP. Barely makes a dent, really.
Out there among the Great Unwashed, I suspect the issue is more about the value they get from reading. People read a lot more than they write, after all. People were already getting tired of watching all their friends' highlight reels. Then since the last election there have been far more fights in comments, and the feeling of being manipulated, and people pretty naturally start to wonder whether this is time well spent.
I'm not dismissing your concern, but I don't think it's particularly relevant to the OP. Barely makes a dent, really.