Sen. Kamala Harris, D-Calif., a freshly minted presidential candidate, sketched an appealing picture of Medicare-for-all at a CNN town hall on Monday. Yes, she said, the plan would require doing away with insurance companies. But, she argued, who would miss them? “Who of us has not had that situation where you’ve got to wait for approval and the doctor says, ‘Well, I don’t know if your insurance company is going to cover this’? Let’s eliminate all of that, let’s move on.”

Actually, no one can really eliminate “all of that” — not Harris and not possible 2020 candidate Sen. Bernie Sanders, I-Vt. Even if the United States adopted Medicare-for-all or some other version of national health insurance, Americans would not get everything they want whenever they want it. No one, in any country, does.

Harris and other Medicare-for-all advocates expect that the country would save money and hassle if the government, not insurance companies, paid for Americans’ health care. Insurance company profits and marketing costs could be redirected to health care. Whether the savings would be as large as expected; whether the government could manage things more efficiently; whether Americans really want to disrupt the existing system — all of those are legitimate questions for debate.

But what Medicare-for-all could not do — and what Harris and others who may tout the idea during the coming campaign cannot claim honestly — is end health care rationing.