I think that a messageboard should for their own sake require your email or cell number for initial sign up and a real name for their own records, but I wouldn’t make it legally mandatory. Besides which, unless you pay a fortune for security it’s easy enough to give a fake name and I personally have a dozen email addresses probably (4 I use frequently, most of them abandoned but to my knowledge still active) so it would be next to impossible to require that. Even if you required a credit card a prepaid Visa can be had at any grocery store.
I’ve given more than enough info on these boards for somebody to find my real name (not a closely guarded secret anyway) if they want or need it, but I much prefer posting under a screen name for many many many reasons. I’ve got more than 20,000 comments on this board alone: can you imagine how many could be taken out of context? Hell, some of them are pretty damning when quoted directly.
My real name is identical (first, middle and last) to a producer of straight-to-video schlock horror movies. It’s also close to the name of a white supremacist who blogs (no relation to me- I’ve even compared genealogies just to see and if we have a common ancestor it was before the 18th century or not in the surname line, thank goodness) and per various websites there are at least 23 people in the nation with my first and last name, so it’s not even that easy to verify which one of us is posting.
OTOH if somebody made threats to kill another Doper and was NonnySnarker3 or whatever, I think there should be a way I could get their real name or at least some actual contact info.