Actually, you're right. Refer to any number of comments about this across the web. Southwest doesn't make money off flying airplanes anymore. Southwest makes money by buying oil significantly below current market prices thanks to an aggressive hedging/speculation program. If that counts as a profit, so does running a toaster loyalty program.

BTW, please take a look at China Aviation Oil Company (Singapore) for an example of what happens when massive bets on the price of oil go wrong.