Really, though, the AFM did not get national power over radio until when Petrillo "took over" and adopted a dictatorial, totalitarian management style which was comparable to what would later be called "guerilla warfare".
Radio converted music from and industry based on sheet music sales... where every bar and honkeytonk had a piano player if not a little band. The hits were just the songs, not the artists. This is why the rights business in the US was always based on composers and authors.
In fact, in much of the free world, until recent decades there has been limited or no rights payment to both artists and composers. In Ecuador in the 60's I paid no rights to either group; the only payments were made by record companies based on sales. I had similar experiences in the Dominican Republic, Perú and several other nations up to the 80's and it's still a more limited system than in Europe and the US / Canada.
Again, the transition from sheet music to recorded music did not adjust well or quickly insofar as getting fees from those playing recorded songs on the radio. Record companies first tried to keep the recordings off the radio and never quite figured out that radio helped them until Top 40 and Black music began to be huge in the 50's. Then, the system fell into place: radio makes songs sell... if you can, however you can, get radio to play them... and make your money off the vinyl.