I appreciate the author's viewpoint, but I think he does not make an argument persuasive to opposing viewpoints. He does not address values, assumptions, and reasoning used by such opponents. The Wally quote and the talk of admired past painters using aids are helpful on a subconscious level, as they are appeals to authority and accomplishment. It would be much more persuasive to directly attack the naturalistic values of opponent. I would challenge the author to develop a more persuasive essay. If it is reasonable to extend the author's argument to cover music, then what sort of argument would he need to offer to convince others that Skrillex has the same artistic merit as Frank Sinatra, which in turn has the same artistic merit as Mozart? Going beyond even that, I would like to hear the author's opinions on algorithmically generated art, like the Mandelbrot set.
The author never mentions artistic merit, presumably because it's a result of his premise. If you can't cheat at art, it's because there's nothing to cheat for, so there's no such thing as artistic merit.
I don't quite agree with your conclusion as written, because I think you can make the point that purely skill-based efforts do not have artistic merit. For instance, the frozen fish packager in an assembly may not be seen as having artistic merit in the his or her endeavors. This is because the effort is not creative, but following a process. It is not meant to provide any aesthetic value or entertainment, but is meant to achieve another objective.
On the other hand, if you mean that nothing intended as art can lack artistic merit, making the concept of "artistic merit" useless in that context, then I fully agree.
