More than 100 House Democrats have endorsed Rep. Pramila Jayapal’s Medicare for All Act of 2019. Fourteen Democratic senators have co-sponsored a similar bill from Sen. Bernie Sanders.

The title is deeply misleading. It implies that the current Medicare system would be extended to all Americans. In fact, Medicare for All differs from Medicare in fundamental ways—with much broader coverage, no cost sharing, and fewer choices of health-care plans. While America needs a debate about health care, it should be based on an accurate...