How Pop Stars Killed 'American Idol'

It's tempting to say that American Idol, which closes out its final season tonight, went downhill after the 2010 departure of tart-tongued Brit Simon Cowell — the music-business lifer who transformed "cruise ship" from a benign vacation locale into a contempt-dripping insult, and who exhibited his tireless commitment to the deep v-neck on primetime television. But Cowell's exit was predated by the real cause of Idol's decline: the decision to offer judgeships to the incredibly famous, who