Sounds like a good book, on a cursory glance.   I'm probably not an unbiased observer, since I've said for decades that 1966 was the peak year for pop music-- (in the rock era--actually the 30's and 40's had the best pop music ever).   Since 1966 it's been just about straight down, and now the slide has become just about a vertical fall.

And "Sgt Pepper" was the first absolutely clear sign of the problem. The Beatles got into a studio, and fascinated by all the dials, started getting "creative".   The kiss of death.

Up to 1966, the Beatles clearly acknowledged the debt to American R & B.   Then in 1967 the overwhelming success --and absurdly overpraising and overparsing ---of "Pepper" encouraged every other 2-bit group with access to a studio to twist dials to create their own "masterpiece".   And everybody, even groups that had no need whatsoever--( since their original sound was far better than the tripe coming out of studios)-- like the Temptations, jumped on the bandwagon.   Then it was a race to the bottom, with technopop and other abominations just around the corner.

I may well buy this book. Always nice to have your opinions published.   Even if you didn't write the book.