Those of you who aren't gamers might not have heard of the RealID incident. Last year Blizzard Entertainment, possibly planning a connection with Facebook, attempted to make its forums and in-game cross-server friend feature use subscribers' real names instead of their handles. Customer reaction was not good and eventually Blizzard backed down in part. In the meantime, people used, um, well, probably Google to dig up lots of information about Blizzard employees from the starting point of just their names. Got kinda messy.
I'm still looking for a definitively readable link on this incident, but in the meantime, here are all the articles WOW Insider wrote about the feature. Reverse chronological order.
Controversy starts here: http://wow.joystiq.com/2010/07/06/official-forum-changes-real-life-names-to-be-displayed/
And ends with Blizzard's capitulation: http://wow.joystiq.com/2010/07/09/mike-morhaime-real-names-will-not-be-required-on-official-forum/
Their motivations were probably similar to Google's. Anonymity and easily-changed names allow a lot of bad behavior people wouldn't indulge in if they had a reputation at stake. Put a real name on a forum troll and he slinks away never to be seen again. But there's that middle ground of the established pseudonym, which has reputation & identity attached to it even though it matches no official passport.