Democrats claimed for years that ObamaCare is working splendidly, though anybody acquainted with reality could see the entitlement is dysfunctional. Now as the law breaks down in an election year, they’ve decided to blame private insurers for their own failures.

Their target this week is Aetna, which has announced it is withdrawing two-thirds of its ObamaCare coverage, pulling out of 536 of 778 counties where it does business. The third-largest U.S. insurer has lost about $430 million on the exchanges since 2014, and this...