Bollocks, as my English friends might say. Commercial country music evolves and adapts, as it always has, even in those fondly recalled "real country" decades. Nashville was putting out a very different sound in all three of those decades, just as it is today. But there have always been traditionalists and genre-stretchers. In the '70s, you had George Jones and Tammy Wynette doing the classic Nashville Sound, Emmylou Harris honoring the genre's past with a reverent "Blue Kentucky Girl," Hank Williams Jr. rocking his dad's "Kaw-Liga" and even Bill Anderson going disco for a couple of singles ("I Can't Wait Any Longer" and "Double S.") In the '90s, country hitmakers included Patty Loveless, Ricky Van Shelton and Randy Travis as well as the Kentucky Headhunters, Mary Chapin Carpenter and Shania Twain. Today, Chris Stapleton and Miranda Lambert coexist with Dan + Shay and Florida Georgia Line.
Nashville's sound has gotten friendlier to younger listeners over the past four decades because it's has to. The realities of radio and advertising demanded that it do so. But to exclude later decades from "real country" is unjust.