> that the decline of a civilization can begin in the decline of its music.
This essay suffers by ignoring the elephants in the room.
Any such analysis must look at how, for example, the Nazis objected to the "weakening of sexual restraint" during the Weimar Republic, and the "decline of ... music" to justify why they needed to take power. - https://en.wikipedia.org/wiki/Degenerate_music
Nor was Nazi Germany unique. Authorities in the Soviet Union and the US both opposed, for example, jazz music; in the US, for the racist view that “wild African jungle music” was a plot to destroy American culture. (Eg, https://archive.org/details/ChristianPatriotsCrusadeF.AllenM... )
This is quite relevant as the author specifically regards jazz music as a sign of not being in decline.
Who gets to determine if music is in decline? She doesn't say.