I used to do this. It was important to me to have purity in thought and expression, free of the binding qualities of social expectations and such. I would share life experience, but not the sex of the relationships I spoke of, things like that.
Others paint a whole portrait on top of one's self if given the chance, oftentimes. Being anonymous in plain sight was preferable to dealing with the generalizations made by either sex.
Someone asked me on ventrilo once, "What are you?", in regards to my sex. I don't like it being used as a lens through which one views another's thoughts, actions and self.