I credit the transition point to the Beatles. They were the marker between traditional pop music and rebellious nihilistic, hateful music. Not most of the Beatles music , but what followed them got progressively more angry and mean spirited.
Country music is even worse. I don't know what year country music died, maybe around 1975 or 1976. It slowly morphed into rock and roll pop. No more Porter and Dolly or Pretty Miss Norma Jean. No more Skeeter Davis, or Dottie West, or Bobby Bare, or George Jones or Hank Snow or … or … or …
It died when the “Pink Hand” moved into Nashville and took over production. I worked for a man who was a “country music Big” producer and he relayed the story of how the place turned into SF of the South, or as he relayed it Hollywood part two.
Country music lost it’s country back in the early 1960s. In the 1970s it became mostly 1950s rock and roll for a while. I still prefer real country music from the 1930s-1964.
Spade Coley
Bob Wills
Hoyle Nix
Slim Willet
Ray Rogers
Butler Boss
Buddy Walker
Tex Williams
It’s the music I was rocked to sleep by on the High Plains.
But then, music must move on or we would be still listening to variations of 15th century chamber music.
Dottie West... I loved Dottie West. I saw her in Vegas as the opening act before either Kenny Rogers or Glenn Campbell. (Obviously I recall the opening act more than the main event.) So sad when she died.
I do not credit the change the Beatles at all.
I credit it to Payola and to openly sponsored shows pushing rock exclusively.