I would say that the original argument is faulty for a different reason, and that is the assumption that the "greats" got there by their photographs. They didn't, they got to noteriety through someone else bringing their work to everyone's attention. People here don't seem to like Alec Soth's work, but why is he famous now? Someone in an important gallery saw his work and submitted it to the Whitney Bienniel, launching his career. Without that he would probably still be a lab tech in Minnesota. Ansel Adams was just a guy with a camera until Steiglitz decided to show his work in his own gallery. There are a ton of great photographers that nobody has ever heard of, and there are a few terrible ones that everyone knows because somebody promoted their work to a large audience.