The U.S. Federal Reserve’s response to the coronavirus pandemic began on Feb. 28 with a 44-word statement of faith in the economy from Chair Jerome Powell, an old-school measure aimed at calming nosediving financial markets. Within weeks, though, its actions became so groundbreaking they cast the U.S. central bank as creditor to the world and open to frightening amounts of risky debt. Even Powell felt the Fed had “crossed a lot of red lines that had not been crossed before.” “We saw the economies around the world shutting down,” he said in late spring, “and we felt called to do what we could.” That included fast promises of massive bond purchases, an open window for dollars for other central banks, and eventually loan programs covering virtually any U.S. business and many local governments. Still, what happened proved the alarmists wrong: The Fed’s balance sheet, a rough measure of its footprint …