Because they couldn't othewise get the info? Because "morons" won't be "morons" without the assistance of FB? LinkedIn anyone? Adsense? Email? Online banking? I'm fairly certain there is some inherent level of danger in anything
that is Internet-based, better get off the innerwebs altogether, then, to ensure your "safety."
My account is totally private; you can't even search and find my name unless you're my friend already. I don't play games; "like" or "subscribe" to any businesses, products, celebs, etc.; or share any other private information that would be useful to anyone outside of my circle of friends and family. So, forgive my ignorance, but I don't understand the clear and present danger. I say "hello" to my dad and siblings across the country...look at pics of my old childhood friends and their children/grandchildren/spouses...occasionally share special photos with my family and friends...occasionally share happy life events that only my friends and family will be interested in.
I reiterate, I realize that nothing is 100% safe...but then, nothing in life is.