Last week, Delta Air Lines announced changes to its SkyMiles program that will make accruing status and taking advantage of perks much harder. Instead of relying on a combination of dollars spent and miles traveled in the air, Delta will grant status based on a single metric—dollars spent—and raise the amount of spending required to get it. In short, SkyMiles is no longer a frequent-flier program; it’s a big-spender program. These changes are so drastic that one of the reporters at the preeminent travel-rewards website The Points Guy declared that he’s going to “stop chasing airline status.” When even the points insiders are sick of playing the mileage game, something has clearly gone wrong. In fact, frequent-flier programs are a symptom of a much deeper rot in the American air-travel industry. And although getting mad at airlines is perfectly reasonable, the blame ultimately lies with Congress. From the late 1930s through the ’70s, the federal government regulated airlines as a public utility. The Civil Aeronautics Board decided which airlines could fly what routes and how …