Rock and roll in the West came about when post-WWII youth were given cars, television, and the mass-produced electric pickup by Les Paul and Rickenbacker.
Suddenly, for the first time in history, there was a race to find out how much independence and influence people of basically immature age could have in the modern era. The tinge of rebellion, the sweat of dance and sex, racial integration and the overturning of the old order… these were their mostly juvenile obsessions, and these were also the serious threats which were wrapped up in that bubblegum doo-wop and malt shop pop about “Open the Door Richard” (he maybe boning in there!)
Teenagers in the 30s and 40s did not get their own cars. Teenagers in the 50’s did. Suddenly they had the power to gather in large numbers, commingle without a chaperon, and make babies in the backseat. And they listened to the radio belting out The Orioles and Bill Haley while they did it.
Thus it was the DJ who was at the heart of the new teen culture, one which could create movements in a way that was not possible before those kids (who had grown up listening to their transistor radios under their blankets at night) were then handed the keys to their own cars.