High-end art prices aren't "manipulated" in some kind of nefarious way, they're just highly illiquid and complicated. The article makes it sound like there's collusion or price-fixing between galleries, but there's no evidence of that.
The author makes the argument that more transparency would lead to lower prices... yet simultaneously implies prices are lower than they ought to be: "One of the worst things a dealer can do is over-price a work because they can’t lower the price when it doesn’t sell."
And anyways, I find myself sympathizing far more with artists than with the rich buyers here -- making a living as an artist is already hard enough! Why would we want to lower what they can make? And for buyers who want less expensive art, there's tons -- just don't shop at Gagosian!
Finally, the article seems to imply that art is subjectively bad now ("rape of dismembered corpses"), but that lowering prices would help fix that. That doesn't follow at all, and modern art on the vanguard is always considered "bad" by the majority at its time -- whether Monet or Pollock.
For anyone interested in details of how the art world really works and why, I highly recommend "Seven Days in the Art World" by Sarah Thornton.