Facebook is real life. You're talking to real people.
As is being confined in your house for decades and communicating with snail mail correspondence.
It's this stupid meme in the society that doing "technology" is somehow "less real" or impoverishing in comparison to things like sports or tourism. But why would it be so?
You mean like Emily Dickinson?
But books are old and socially admired, so no-one who complains about Facebook also complains about books.
Of course, there are probably people who don't care what other people think about them on Facebook and are just totally open. But I don't know any of those people.
Well, that's what you do. Others just write what they think and share what they life, caring only slightly to stay within the cultural norms. Exactly like in real life. There are lots of people who are calculating how they look, what they say, etc. in physical world as well. "How will people interpret this? Will it project the right image of me? Will my net opinion be increased or decreased among my friends' by this action? Is it compatible with current and/or future employers?" are they questions they ask themselves all the time.
Well, always. But they're not always who they claim to be!