Not long after his appointment as chairman of the Federal Communications Commission, Norman Minnow famously delivered a keynote speech at the annual convention of the National Association of Broadcasters. He challenged the television executives gathered in the convention hall “to sit down in front of your own television set when your station goes on the air and stay there, for a day, without a book, without a magazine, without a newspaper, without a profit and loss sheet or a rating book to distract you. Keep your eyes glued to that set until the station signs off,“ he said. “I can...