First of all, great topic, Kevin!
I kind of grew in this subject... At first, after I read a story, I mostly didn't comment. Why? I didn't want to be noticed as a reader, because I was really deep in the closet! (Of course, this applies to the stories on GA) But, now that I'm coming to terms with myself, I try to comment on the stories I read. Why? I once wrote a story, got no replies or whatsoever and I just quit it. So I know somewhat how it means to not receive any comments.
In a way it is kind of frustrating as well to have all these stories here! And to see that some authors are bummed about not getting any/much comments! And that's because I have other duties and occupations as well, like studying, or going out with friends, going to school, etc... So I can't read every story! And so I can't comment on them! And it frustrates me to no end...
I do think, if you want more comments, you still need to sell yourself and your stories... Only then can we notice you really DID write something, and we get curious as to what kind of stories that person writes, and if they're any good, and if it might thrill us to wait for new chapters to be posted! So authors, if you're desperate for comments, become visible!
Cheers
Niels