There were many contributors to the 2008 financial crisis—including unsound housing loans and mortgage-backed securities, Fannie Mae and Freddie Mac, excess leverage by major financial institutions, and regulatory failures. Car and truck loans were not among the problems, and their lenders in any event pose no "systemic" risk to the financial system.

And yet, amazingly, the Consumer Financial Protection Bureau—a creature of the Dodd-Frank Act, which was passed to correct and prevent the causes of, and problems that...