On his last night in the anchor chair at a political convention, Tom Brokaw of NBC was feeling resigned. The conventions, he said in an interview on Thursday, were mere "infomercials," with little to interest anyone beyond political partisans. "These events are managed down to the last semicolon," said Mr. Brokaw, who is retiring after the election. "That's why I find it hard to climb those stairs and get into the anchor chair anymore." Like Mr. Brokaw, a number of television executives yesterday blamed the Republicans and Democrats for the networks' dwindling convention viewership. But as the Fox News cable...