Like a guy giving career advice for engineers in Germany always says (I'm citing indirectly here, so there maybe is a certain spin to it): Nobody is blamed for following the "rules",so if HR doesn't get good people or any people at all they won't be blamed as long as they followed the rules. On the other they WILL get blamed if they hire the wrong or too troublesome people.

Maybe they think stalking prospective employees via facebook helps them somehow there...