It will come as a huge relief to millions of Americans that Republican lawmakers have struck out in their attempts to destroy the Affordable Care Act — at least for now. But this ideological exercise in futility has already done great damage to the health care system.

First the good news, which came in two installments: No. 1, the Senate’s health care bill — which would have stripped 22 million people of their health insurance and increased premiums for older Americans and those with pre-existing conditions — collapsed Monday. Then, Tuesday, Mitch McConnell’s plan to repeal much of Obamacare without a replacement also fell apart as senators defected.

Now the bad news: While the Affordable Care Act is not collapsing, the Senate and House health bills and President Trump’s promises to sabotage the A.C.A. have destabilized some of the health insurance marketplaces created by that law. Nearly 40 counties in Indiana, Nevada and Ohio are at risk of having no insurers participating in the marketplaces next year; other counties will have only one company offering policies.

In addition, policies sold in the marketplaces could cost a lot more if the Trump administration carries out its threats to stop providing subsidies to insurers to lower deductibles for low-income and middle-income people. It can do that through administrative action. House Republicans sued the Obama administration to block the payments on grounds that Congress had not voted separately to appropriate the money, even though the A.C.A. had authorized them.