"But broader forces are also at play. Nearly 30 years ago, Sherwin Rosen, an economist from the University of Chicago, proposed an elegant theory to explain the general pattern. In an article entitled "The Economics of Superstars," he argued that technological changes would allow the best performers in a given field to serve a bigger market and thus reap a greater share of its revenue. But this would also reduce the spoils available to the less gifted in the business.
The reasoning fits smoothly into the income dynamics of the music industry, which has been shaken by many technological disruptions since the 1980s. First, MTV put music on television. Then Napster took it to the Internet. Apple allowed fans to buy single songs and take them with them. Each of these breakthroughs allowed the very top acts to reach a larger fan base, and thus command a larger audience and a bigger share of concert revenue."