I've noticed this belonging to a few communities that blend online presence with professional interests, and I've often wondered what kind of confusion was waiting for someone who did all their networking/advertising/foruming under a name like LOLcat123 or SONICfan and yet never credits the comic to themselves. "MY GREAT COMIC by ladygagagirl" I think to myself "When they go to a con, what do they write on their name tag?"
I don't necessarily think that people should always use their real names as screen names, though it does make for less confusion, especially in a place like deviantArt. It's made a lot easier, too, when your professional name isn't your real name, which is something I encourage people to do. Gibson Twist isn't my real name, but all my work is done under it. It's probably good to have a screen name that's at least close to your professional name, like Ran or Rob, then it's a lateral move in thought for readers. I would say that if you're using a different name in networking than you want to be known by professionally, you should make damn sure your real name is on your work in big, bold letters.