The Rock and Roll Hall of Fame opened and started enshrining artists in 1986.
Twenty years later, the judges — or whoever puts people in —discovered Miles Davis and decided "jazz" was a part of rock. A year later, someone told them they might want to look into this thing called "rap," so they put in Grandmaster Flash and then Run-DMC the next year and decided that was a part of rock.
Apparently, country is not rock. What about Boy Bands? Rock or not rock? Should there be a separate Boy Band Hall of Fame? Better figure it out soon, or we'll end up with another disaster like this: