In 1979, a community radio station, WMNF 88.5, was launched in our humble hamlet.
At that time, they played jazz in prime time, 7-10 if not 7-11, Monday through Thursday (possibly more.)
Each night of the week featured a different host, and as a result, different aesthetics and musical/cultural perspectives.
While most of the jazz DJs were white, the Thursday night DJ was an African American gentleman by the name of Charles Van. He played primarily organ grove. As a white kid (That is not me in my profile pic; I'm not that handsome), I had never heard this music before and was mesmerized.
I didn't know it at the time, but Charles Van was playing this stuff 10 years after it had gone out of fashion, and 10 years before hipsters rediscovered it.
Anyway, my anecdotal experience seems to reinforce the book's thesis. The "jazz" that anyone was talking about, writing about, or listening to at that time was all very "serious." But I could tell instinctively as a teenager listening to this organ groove stuff that it was party music.
Fast foward another 20 or so years. In the late 1990s, I was living in Beantown, and Ms. TTK and I went to a small jazz club in Roxbury - forget the name of the club - where there was an organ trio playing. The audience was a blend of both demographics - younger white hipsters getting into this stuff, and older African American couples who were probably spinning these records 30 years earlier.