So what do work requirements do? At best, they encourage people who were going to work anyway to do so a little sooner, perhaps shaving a few weeks off the time they are unemployed. But more important, they terminate needed benefits for people facing significant barriers to employment.

Supporters of work requirements claim that the rules can be structured to exempt people who can’t work, but that doesn’t happen in practice. “It can be difficult and burdensome for people,” explained Hannah Katch, a Medicaid expert, “to prove to a state bureaucracy their inability to meet a work requirement that has been imposed on them.”

As their experience under welfare’s work requirements demonstrates, people who are caring for family members or who have health or mental health impairments, limited education or criminal records, or who lack access to support like child care would all be at risk of losing their health care if a Medicaid requirement were passed.

To be sure, providing work opportunities is a worthy goal, especially given the extent to which anti-poverty policy is already tied to work. What is needed, then, aren’t more sticks, but more demand-side policies to provide enough decent jobs.

Too often, though, proponents of work requirements assume that all it takes for a poor person to get a job is to want a job. But while the overall unemployment rate is now low, many people face clearly inadequate opportunities, such as those in rural areas and those with criminal records.

On the supply side, benefits like educational assistance, job training and child care assistance also enhance opportunities, as does health coverage itself, especially for those struggling with addictions. In this regard, President Trump’s budget and Mr. Ryan’s Medicaid-slashing health care plan push hard against labor market opportunities for the poor.

By-the-bootstraps ideology may be appealing to some, but it can blind people to the reality that jobs aren’t always available to those who seek them and that many people who might otherwise want jobs can’t take them because of the various obstacles they face. Offering them help to find those jobs while simultaneously ensuring their access to health care is the best way to create a humane, efficient labor market.