Because the internet is a big place, and not everyone can be upfront about the stuff from this site in their real life. Also, it's irrelevant for most of the posts on here. And for some of the ones were it WOULD be relevant, it could also be self-incriminating.
There's also the fact that not everyone is on here to socialize, and not everyone wants to be getting PMs from every pervert who thinks you're within driving distance of them.
Short answer is that not everyone's life can afford to revolve around their cock.
