If health care is an oligopoly it should be regulated in proportion that it behaves like an oligopoly.
One reform would be standardized evaluations for performance of doctors and hospitals. This would surely cut down on lawsuits for malpractice and other abuses. States could administer the measuring of performance with regular reporting. Published reports could take care of a lot of quackery and substandard hospitals. Think of it as a batting average for doctors.