Real insurance involves a gamble. You pay a small amount to get what is essentially a lottery ticket. You win if disaster happens, giving you money to deal with the disaster.
Would you buy a lottery ticket if it was known to be a winner? Sure! Would anybody want to sell it? No! That isn't a viable business model.
What you are looking for is more like welfare. You have a problem, there is no gamble, you don't have the money, and you expect "society" to pay. That definitely isn't insurance.
Those are the options: insurance, welfare, self-pay
Imposing a duty to handle pre-existing conditions on "insurance" companies is forcing a business to provide welfare. Obviously, people will switch from the cheap company (or none) to the high-quality company when they get a problem. The tax on people without "insurance" is intended to discourage this, but it is ineffective because "insurance" costs more and because people will still switch from cheap to fancy.
In any case, we've invented some pretty fancy health care. Giving it to everybody would exceed our GDP. This is obviously unworkable. The situation only worsens as we invent more. How do you propose to limit usage, if not by price? Would you just promise everything, but let people die on waiting lists? Would you rate and rank people, perhaps on a point system with extra points for politically-connected people?