The Vanity Fair–Bloomberg cocktail reception that follows the White House Correspondents’ Dinner, held at the franco-swank residence of the French ambassador, is the kind of party where Katie Couric can kick off her shoes and spend much of the party in bare feet. It’s the kind of party where Charlie Rose and Ashley Judd stand by one of several bars and engage in a lot of intense close-talking. It’s the kind of party where one waits in line to use the loo, just as one has done at every normal, far less glitzy house party since the 1990s. But then...