I think Facebook has thought this stuff out quite well: When people use real names on their service, it's easier for family, friends, and college acquaintances from thirty years ago to find them, thus increasing user engagement with the site. It also gives them an easy excuse to delete troll accounts. Furthermore, having people's real names (and often address etc.) makes them a more attractive target for advertisers. Most of the Facebook biographers seem to agree that the real-name policy was one of the factors that helped it win out over MySpace and other social networks. (Among many, many others, of course.)

In light of how much money this policy is presumably making them, and considering that they have about a billion customers who seem to accept the policy as is, I strongly suspect they don't care in the least that the occasional person with an unusual name falls through the cracks, or that they're screwing over people who need to remain anonymous for legitimate safety reasons.

Do I agree with their decision? Not at all. But I think they know exactly what they're doing.