I would argue that it's more the old argument that real art comes from pain, from misfortune. Think of
the Blues, think of
Jazz, think of
Gospel--all born of the oppression of African Americans. Think of early
Rock n Roll--same thing. Even the whites who latched onto rock were either poor (
Elvis) or emotionally unstable (
John Lennon).
Great art is born of pain. Think of Ulysses--brilliant, dealing with oppression (Irish under English), racism (Jew under Christian), adultery (both Blooms), and twenty-something angst (Stephen Dedalus), written by a jealous alcoholic. Think of Huckleberry Finn--a reaction against the Guilded Age, and a response to Reconstruction, written by a man who suffered from severe depression and self-doubt.
Think of the Sixties--great music. Why? Civil Rights, Vietnam, assassinations, you name it. Think of punk--the Seventies and Eighties were economically near a depression. Think of the early Nineties--same deal.
And notice that grunge died with the expanding economy. It's not just the record labels cutting acts. It's the mood of the populous. People are less willing to think when things are good. They don't march in Prada, they march in Chuck Taylors.