Medical care, like all resources, must be rationed somehow, since demand will always rise to exceed supply. As long as it was available only through the market, there were always those, the very poor, who simply could not afford all they needed. In nations where it is not provided by the market, the rationing occurs in other ways.

The problem today is that rising costs are now making the population that cannot afford it larger every day. It is no longer just the extreme poor, but the working and middle classes that are now being threatened by financial ruin due to a medical emergency. I heard the other day that medical expenses are now one of the leading causes of bankruptcies in the US. These are not lowlife welfare cheats, these are people who have built this country.
And it could happen to any one of us.

The point is that the free market is simply not doing its job any more, an alternative must be provided. If the market were working, this debate would not even exist. In other countries, the state takes on this role, and in spite of the problems that are bound to arise in any bureaucracy (even a decentralized and predatory one dominated by megacorporations and medical asssociations, like ours), the system works, in spite of the shrill allegations of those here that all those other countries' medical systems are in a state of catastrophic collapse.

However, I don't think this necessarily means that the US can easily replace its present health care system with one that is competent, affordable and humane. Those who benefit from the current system, whether as users or providers, will do anything they can to sabotage any reforms, or to take advantage of them for personal profit.