Why would a $10-$12 hour job for Mosaic Sales Solutions ask for link to your Facebook?

Since when did it become acceptable for a part time employer, paying 10 - 12 bucks an hour for a 20 hour job, to ask for a link to any Facebook, MySpace, Linkdin account? What exactly will this link show? I have a locked down profile, nothing I'm ashamed of but yes there are personal pics, etc. reserved just for friends and family... I understand drug test, background test, but this? Ideas?