1) Why was this necro'd?
2) Fairly simple. Mating is a natural human process to continue the species, at it's heart. Being more advanced than mere animals of course, we often do it simply, well, because shit feels good bro.
However, that instinct is still there somewhere. Thus, someone failing to get laid, even only for recreational purposes, becomes someone failing to be a functional human being.
At least that's how I think it works, being a complete perma virgin myself. Hell, I downright believe that I have failed to be a functional human being, everyone else I know has managed it, it can't be that hard, yet I fail to attract anyone.