This is like saying long exposures don't count because they're composite images
All photos have an exposure time; that's an inherent property of them (think film). Compositing images digitally on top one another is not an inherent property of photos.
You can double expose film, and I think that's a finer line, but I think the distinction most people care about is really analog vs digital.
Even multiple exposures of one frame of film is, as far as I can tell, still generally considered one photograph.