I don't know why lesbians (as characters, I don't know author orientations in general) are so pervasive in the webcomics world, but they surely do seem to be so. Gay fellas seem to get rather less of a fair shake, unless you count Yaoi, which I don't.
I'm sure I'll natter more about this in the future. But not The Future, because we all know we'll have discarded such primitive labels by then and be bicarbosexual or something.