The author blames bad math grades (apparently) on the math education being stupid and boring. The author neglects other ideas that could be responsible. Also, the author never explicitly stated that there was a bad math grades problem in the first place, but leaves it to the reader to infer what the problem is. It could well be that the reader incorrectly infers what the author is saying wrong about the outcomes of math education; but whether or not the author intends it, the likely inference that a reader would have is that there is a problem with student math grades, or perhaps skill assessment scores, being too low.
Most peculiarly, the author now leaves behind the math-as-art metaphors, and does not write that math is like an art or has creative aspects akin to art ,or that the learning of math is analogous to the learning of art, but explicitly states that math is an art. The statement is absurd.