Is music really mass produced repitition?

When reading through the articles discussing the theories of the School of Frankfurt, I couldn't help but feel a little irked at the idea that they felt all pop culture was mass produced, repetitive, and -- more or less -- watered down remnants of "true" art. Afterwards, I started going through most of my music collection and carefully considering the music behind the lyrics. I had to realize that most of the music within a genre could be considered reflective of each other. Often the same band had a handful of songs that sounded very close to each other.

Then I remembered a fairly well-known parody music artist who has made it his career to mock the most noted of pop culture music -- Weird Al. He's made it a tradition of his to produce medleys of all recent pop music into a string of the same polka music by just altering rhythm and tempo. He proves that he can take just about anything and duplicate it, either just lyrics or into a completely different genre from the original.

This material would lead to me agreeing to the views of the School of Frankfurt, yet there's more I see in pop culture that I feel still contradicts those ideas.

There is a popular musician/artist that has exploded in fame through the music videos she has posted to Youtube. She started off mainly doing covers of popular and famous songs by integrating two very different music types -- classical... and dubstep. Lindsey Stirling, while perhaps not the first to accomplish this, managed to create something new from two very opposite ends of music culture and that certainly does not sound "mass produced".

From what I gathered, those of the School of Frankfurt viewed that anything taken from "true art" and implemented into pop culture would be considered cheaply imitated. Can that really be considered the case when you take the refined classical notes of a violin and implement it, artistically, into popular music? Can those of the School of Frankfurt truly cry that all pop music is the same, dull, repetition and not the works of the refined, classical works of Beethoven and Bach?