I looked at a couple of random 80's boos as and the statement that you base your assumptions on is not really true.
1982. WCAU FM was tied with WMMR in 18-49 and way ahead in 25-54. An in women, they dominated.
In the mid-80's WMMR was dominant, and WCAU had fallen but there was also a fragmentation of CHR shares with a second competitor.
By the later 80's WEGX had gained enormous traction under Malrite and was beating WMMR in the Female demos and was a serious overall contender.
While, for the decade, WMMR was a big station, it was a ten-share big station and 90% of listening was not to them. Saying that a classic hits station shoul emulate their playlist is suggesting they should change to classic rock, a niche already occupied. CHR stations have generall y been huge cume machines with shorter TSL... so the music they played was more widely exposed.
So CHR music was definitely familiar, as those stations were always huge comers, while 'MMR was more of a. TSL play.
The reason PHX stations don't play the local "hits" is that back then the market was less than 2 million and now it is over 4 million an at least half the people are not natives or were not there in the pertinent 80's years.
"Flow" affects TSL, not cume. Cume is driven by format and general playlist feel as well as talent, promotion, etc.
In general, Sunbelt markets will have a lot of growth and migration, so the playlists will not have much local feel. Low or no-growth markets will be able to localize as the population is stable.
I attempted to counter the argument you made here before you made it as I seen it coming, maybe I wasn't clear enough. What they are doing now is about cume, I'm saying that you don't need to lose any cume by carefully adding in market appropriate hits along side the tried and true. In effect you can keep the cume as it is, high, but create longer time spent listening and more instances of listening as well. I'm saying you need to add a pinch of salt to your stew for flavor, that should not be interpreted as me saying dump the whole box of salt into the stew and remove the beef.
It seems logical that NYC's classic hits station should lean a bit more rhythmic based on market history while Philly should lean more rock based on its history. I'm not talking about changing to classic rock, WMGK does that really well already, Classic Hits station are first and foremost mass appeal, it should be the hits and that will be a variation of sounds, but the slight leans make a difference and those should be based upon knowing the market and playing to that market. Also, those regional hits are obviously not going to get any type of top rotation, that's suicide as obviously markets change over time but you can spike a few regional hits for flavor and create a passion for your station that you just won't get by a 24/7 safe and mundane playlist.