Traditional jazz doesn't make use of the IV of the scale much. It was used as a passing note. A passing note is a kind of bridge note that is used to string notes in a chord when those notes are played sequentially rather than simultaneously. A ii-V7 of, say, D minor 7 and G7 could be played on the bass or the piano left hand as ascending CDEA (1,2,3,5) of C minor 7 and then descending as GFED (8,7,6,5) of G7. The passing note is #2 or D as it is not part of the C minor 7. Then it turns up again on G7 as #5 of which it is part. It is #6 or E that that is passing in G7. Since a chord is 1,3,5 then the passing notes would be 2,4,6.

In bop, however, the 4 was prominent and not just passing. This drove the traditional jazzers crazy. Emphasizing the IV???? Why, that's the end of jazz! The boppers have killed it!! Even now the traditionals and neoclassicists disparage bop and refuse to play it. That's one kind of snobbery.

There is also a cultural snobbery that permeates pop music, one reason I'm not dying to defend it from attack today and often attack it myself. It is a bastion of snobbery that dates back to the 60s when suddenly all forms of music from the previous decades were simply ignored. When I grew up in the 60s, I rarely heard anything from the 50s, most of which was considered a joke. And nothing from the 40s was ever played despite about 90% of America's songbook being songs from the 30s and 40s. Oldies stations specifically advertised themselves as playing music "from the 60s, 70s and 80s."

Not until the advent of satellite radio was 40s and 50s music resurrected. Today's oldies stations play a bit more 50s to compete with satellite but nothing from the 40s. All pop today is descended from the 60s or later and so has that snobbery built into it. It sees itself as all there is. As a result it is a largely degenerate music just as anything with an isolationist policy degenerates. And that is the reason it will not be remembered in 30 years. It's not worth remembering. Just see if I'm wrong.