Frank Sinatra was a big part of creating a distinct youth culture. In the 1940s, his unprecendented and exclusive appeal to adolescent girls set the stage for Elvis and then the 1960s youth movement.
But in the 40's the whole family would listen to Sinatra on the radio. If the radio played something the old folks didn't like, they could turn the dial. Once a kid could take the radio with him, the media could focus on kids exclusively. They could peel the kids away from the herd.