Clay Shirky, weblog A-list type guy, has a post up about how the distribution of attention/money/etc in a system where there is maximum consumer choice and relatively low-cost entry for producers is a power law. Specifically he's writing about how as more and more people write and read blogs, that the "star" blogs will attract more and more attention and it will get harder and harder for new bloggers to "make it."

You could substitute the word "webcomic" for "weblog" in his article and see an argument for why several top-tier webcomics have risen while most (of varying quality) have stagnated viewer-wise.