People making this argument tend to want 'better health outcomes for millionaires/healthy white collar people', either because they are one, or they think they will be one.
What I always point out is that markets are a form of rationing too. They are just form where people with money are allocated more goods than people without it, sometimes to the total exclusion of large parts of the population. Given that we set up polities for the common good, I'd argue that any necessity which markets fail to deliver to everyone should use some other kind of rationing strategy.
