These composers (Schoenberg, Berg, Webern), all of whom were thought to be highly abstract and intensely intellectual and extremely challenging, would have been instances of pure music of the sort that Greenberg would have valiantly championed. This was stuff which was quite simply way to challenging for most audiences, especially American audiences.
During WWII, when all this stuff was condemned in Nazi Germany as hyper-intellectual and decadent “Jewish” music, these composers came to America. And of all places, they found themselves, along with other leading German-Jewish intellectuals, in Los Angeles, making music for Hollywood motion pictures.
Prior to the war, no Americans would have been able to abide this inchoate noise (which, in fact, is strictly rule determined). But, co-opted, watered down and used as background for suspenseful scenes of the sort we’ve come to expect in psychological dramas, advanced music, suddenly, made sense. Hitchcock’s films, which helped domesticate that other “dangerous” Jew, Sigmund Freud, is the best example of how capitalism cannibalized the avant-garde and high art, or at least a facsimile of it, incorporated it into Hollywood.
This is the cinematic equivalent of Jackson Pollock’s shocking splash-and-drip paintings making their way into Vogue magazine, as backdrops for fashion models, and in the artist’s own lifetime. Greenberg was outraged.