That is like saying only painters should be able to visit art galleries.Personally I feel that only other authors should really be able to review stories. They'd then know how much time and effort people really put into their work.
I am not a writer, but I like to read. I have a right to post a review here, just like I can buy a book at a bookstore or buy a CD. That is one way I can say whether I like the story.
As a reader here, I should tell the author why I like or not like the story, not blame the story codes - you're right there.