There have always been lepers. And vagabonds. And beggars at the temple gates. So your linkage makes no sense.
What you ignore about health insurance is that you use very little in the first 50 years of your life, much in the next 15, and a lot in the last 10. So a mandatory plan that included young people in the risk pool would avoid the problems of adverse selection. The only way the risk can be bearable for an insurer is to include lots of young people.
And don't ignore the fact that "reasonable and customary" involves a continual dialogue between insurers and health care providers. Insurers routinely game the system by saying to doctors, "If you settle for 70% of your fee you can have it right now but if you want the full amount the bill will have to go through a lengthy review process." Generally the doctor says, "fine". It's a game they play in billing. So don't assume insurers are in any way at the mercy of health care providers. The insurer, after all, controls when the health care provider sees his money and that is a lot of leverage.
Oh goodie, yet another forcible transfer from the relatively poor young to the relatively wealthy elderly. No thanks.