>the contention that Bob Marley perfectly
>encapsulates all things that are reggae whereas 'rock' is much
>too nuanced and multi-layered to be represented by just one
>person.

you're completely misrepresenting his stance here.

what he said is that the way collective mainstream memory works w/r/t musical culture is that the fringes are forgotten, one individual eventually emerges as emblematic of an entire genre, and their accomplishments accordingly become exaggerated over time. see bob marley in reggae or kurt cobain in grunge.

he's contending that the difference with "rock" (as with jazz before it) is that as an ideology it's transcended its musical-genre origins to become definitive and pervasive of society as a whole in so many non-musical ways. hence the fact that we use words like "jazzy" and "rock-star" as adjectives to describe things that literally have nothing to do with music, in a way that we don't use the word "reggae".