Facebook is opening yourself up to all kinds of narishkeit. It is NOT a place for someone that wants to guard themeself and their family from the garbage that is out there.
You could say the exact same thing about the internet itself. Instead of calling for people to delete their Facebook accounts, why not call for everyone to stop using the internet completely? Where are you going to draw the line?
I myself am not deleting my Facebook account. I have undertaken to learn an extra mishna a day until the shloshim in Leiby’s memory. To each his own.