I still don't believe it's as simple as all that. I think the basic ingredients of the Chuck Berry, Elvis, and Buddy Holly "Rock 'N' Roll" are still very much a part of the AC/DC, Led Zeppelin, and Van Halen "Rock".

The amps were louder, the chords were more simplistic, and the sexual innuendos were more blatant, but it's still basically the same idea. Hearing country in it doesn't matter. I can hear jazz, country, blues, classical, funk, and world in any of the big name "rock" bands.

It's like the difference in Paul Whiteman's Jazz and Miles Davis' Jazz. They are still Jazz, no point in adding a subcategory to it to separate them.