Please correct me if I'm wrong, but I think the argument of whether photography is art or not was originated in Walter Benjamn's theory/essay called "The Short History of Photography."

Basically he was concerned about the future of the mass preproduction of images. Compared to painting and everything else that's called art back then( this was 1930's), in his view, it was so questionable to call photography as a method for producing art.

But more or less, some people talk about photography not being art or whatever, and most of the time that's pure nonsense. I think photography is photography just like craft is craft. But if it goes a step further and becomes more than just photography to someone, then we are talking about art.