As I recall, you didn't even know that The Edge switched from Active Rock to Alternative long ago. Compare the Edge playlist to ALT Buffalo. They are pretty much the same and similar to other markets.
It's always been that way. In any specific format, particularly today with the influence of the
WORLD-wide-web, the principal hits are the same not just in any US market but in any part of the world where English language music is popular. It's just that the synchronization is faster today.
I've mentioned it before, but when I owned a Top 40 station in Ecuador in the 60's, I used the WIXY and WQAM lists to guide my selections, and had a one-stop in the US send me all the ads each week. Billboard took four to six weeks to arrive, so I used the airmailed station lists as guidance. I'd eliminate music that was too country, too folk or too novelty, but otherwise we mirrored the average Top 40 in the USA.
My point is that a hit is a hit is a hit. Always has been. So stations that play the hits (and gold is only played if it is still a hit and has not stiffed out over time) are going to be amazingly similar whether in Syracuse or Salinas.
I don't know what Cumulus stations you are referring to. Pick any format anywhere and it will be about the same. You defend your precious 97 Rock as some unique playlist, but the facts prove you wrong. Classic Rock is almost identical nationwide with very minor differences. Alternative was Rock oriented in the 90s and actually featured bands that AOR or Classic Rock stations wouldn't play. The name "Alternative" really means nothing anymore...
Hint: it's always been that way, back to when stations all over the US started copying KOWH and KLIF.
So, of course music stations will play the same songs in the same format. Back before the Internet and BDS we used to subscribe to Gavin and FMQB and R&R and all the rest to see what others in our format were adding and dropping. We did not want to miss a good song and did not want to play a song others were dropping.
Heck, even back in the 30's if one orchestra started playing a song regularly, the other orchestras would pick up on it. People like to hear hits, and it turns out it is pretty easy to figure out which are and which are not. Even in the 50's, national television knew a hit when it heard one, and that was why "Your Hit Parade" with Snooky Lanson and Giselle MacKenzie and the others sang the same few songs on the
national network over and over until they dropped off.