All of this is why the natural gravity in a single-payer system is toward brute-force price controls and rationing to control costs.

This wouldn’t be popular, nor would the radical change that Medicare-for-all would entail. President Barack Obama had to promise that if you liked your health care you could keep it because any change to private insurance is so toxic. Medicare-for-all would replace the employer-based system entirely for more than 150 million people. It wouldn’t matter how much they liked their insurance — it would be gone as a matter of definition.

It’s hard to see Medicare-for-all as a plausible health-care agenda even if Democrats swept all elected branches of government in Washington in 2020. But the first step toward achieving any policy goal is creating a national debate over it and swinging one of the major political parties behind it. Bernie Sanders has had considerable success in that effort, and the allure of “free” health care — like free anything — can’t be discounted.