Blame the Telecommunications Act of 1996.
There was a provision that allowed corporate consolidation of of radio markets around the country. All the program managers at these small stations were fired and programming decision went to corporate headquarters.
That eliminated any chance for unknown acts to get on the air.
Tom Petty and the Heartbreakers - The Last DJ
https://www.youtube.com/watch?v=6Knw_GxXPHg
That's part of it. Eternal copyright isn't helping either.