The problem here is one of balance.

As with so many situations where you have unreasonable corporate behavior the problem is the economics favors making wrong decisions. Thus there will be little attempt to prevent those wrong decisions. The only real fix is to make wrong decisions cost--look at airlines. You end up with more passengers that seats, you pay. It went a long way towards addressing the problem. (But it should have been higher and it should be indexed to inflation.)

But note the insurance is not always the bad guy. Patients want things that aren't medically warranted, especially when the right answer is "do nothing". And doctors like to run up the bill.

And note this article is focusing on things other than medical decisions--but describing a system that could only be a problem if they are making wrong medical decisions. How they decide what claims to examine is irrelevant, what matters is if they are making wrong medical decisions. It very much needs to be considered the practice of medicine and a denial should only come from someone of at least the same specialization as the doctor making the request. And "not medically necessary" should require an evaluation of why, you don't get to just say "no".