I know I was guilty of not reviewing stories before I began to write my own. As an author, I do take note of any reviews I get and try now to at least review the stories I get time to read.
One of the ironic things I find though is that the more stories I write and the more I get involved in the forum, the less time I have to read and review! I guess it is a case of just trying to find a balance and I will always try to do that, as writers deserve the feedback.