were true insurance, you'd play for standard medical items on your own and use insurance for the extreme cases. This would bring the cost of healthcare and insurance down because people could shop around for regular services. The free market would limit what the everyday consumer can afford.
This is the same reason college costs so much. In 2010 the ACA passed that said that only the government could do student loans. Well, if the government is backing all loans, the universities can charge as much as they can.... and they have. (A little more complex than this, but...).