Why would an insurer who denied all claims have any customers? I think you're missing the market competition aspect of the insurance business.

Most people do not get to choose their own insurance company, they just get whatever their job picks. Most big companies have directors and officers that personally benefit when a particular insurance company does well. The market is completely broken.

Insurance is an arbitrage leach at best, and extortion at worst. It provides no value to society.

Without insurance Market prices would drive down the cost of healthcare.

I was presenting an extreme hypothetical to a make a point that the insurers are motivated by selfishness.

In the real world, not a hypothetical, your market driven approach ensures they approve the minimum necessary to prevent customers from leaving. They require patients to to fight them for coverage while they're undergoing cancer treatment, because a dead patient they didn't pay out for is more profitable. Paying for insurance in a for-profit marketplace isn't paying for health coverage, it's paying for a CHANCE at health coverage, and you better be willing and able to fight for that chance while you're undergoing cancer treatment/surgery, or be willing to go bankrupt, or not get the treatment and die. That's the choice the insurance marketplace presents to you.

Not hyperbole, many such stories. My own father in law died in part because his private medicare advantage plan refused to approve in-patient rehab after a brain surgery that every MD working on him said he needed, but would have cost 6 figures out of pocket that nobody could front. The grim irony is he later tried to get out of bed to use the bathroom, couldn't support his own weight and suffered a skull fracture that resulted in a second brain surgery inside of a week, and that was fully covered.

I'll take the bureaucrats. The real world shows they're simply better at this, and Ayn Rand is simply wrong.