I would say all music has a qualification as to what genre it is, along with it's many subdivisions, (and I'm just using rock here) Heavy Metal, Grunge, Hard, Acid, Pop, New Wave, Punk, etc. And it's pretty predetermined on how it's sold (Rock Artists in walk in and on line stores) it's awards (Best Rock Album, Best Rock Song, Rock N Roll Hall of Fame) it's distribution (Rock Stations, Rock Concerts), it's biographical history (Rock-n-Roll's Top 100 Artists, The History of Rock n Roll, rock music reviews)...just to name a few, yet enough, that if a person is frequently found in the above examples based in fact, and not of opinion, I'm feeling quite certain, beyond a reasonable doubt, that they would, and should, be considered a rock n roller.
And the same for every other type of music, be it country, polka, classical.
You're telling me you don't understand the qualifiers, I find that hard to believe.
Now that was easy...how bout someone proving it's not real rock?