Back in the 1920s, sheet music was the main distribution for songs, a friend, a gifted so and so, would sit at the piano and play popular songs of the day, and the family would gather round the piano and sing along. The charts were the best selling sheet music.
Recorded music and the phonograph changed all that and I bet if you went back in time and discussed it with the folks than they would decry the immediacy of performance of the music in moment, it would wrench and they have the point, just like punk promised, if you could just play you were a star, you were the center of attraction.
This doesn’t happen really till the turn of the 19th century but by the jazz hit, it was over for sheet music, by the time of rock and roll, 50 years later, sheeted music as a primary form of music distribution was over forever. It is hard to imagine a bigger change than that it is hard to imagine rock and roll with sheet music as the form of distribution. There would be no reason for it. This, as much as the ability to cheaply manufacture guitars, gave birth to rock and roll.
Fifty years later, file sharing killed the recorded and distributed on any medium business. Still in its death throes it is over and that is the biggest change in music since the phonograph. It is huge because it gutted the business financially but also because of its low range of sound it made EDM the prominent form of music, loud became very important when the frequencies were no longer there, beats took over from melody when the melody became muffled.
The result was bad for rock and rollers who couldn’t live without the old verities. But it wasn’t necessarily bad for music though it was hugely difference. But the larger question is: does distribution effect music? Without sheet music would the piano be the prominent instrument at the turn of the 19th century, and without recorded music would the guitar have taken its place 50 years later? And without file sharing, would beats matter so much?