I thought Kris Kristofferson answered the problem long ago when he did his own song - Me and Bobby McGee proudly announcing “if it sounds country - that’s what it is, it’s a country song”.
The whole idea of genres in music was made up by industry types to control artist. They needed to attach names to genres so they could then pronounce company backed artist as “the #1 selling or a real up and comer” in that particular genre and make up silly list of whose top 40.
It’s silly to say an artist is or isn’t country - the basic elements were refined by country music legends. Buddy Holly was undeniably country as was Jerry Lee Lewis - and it’s very easy to trace their influence on early rock. Between country and blues - the 2 influences converged into rock and rock just evolved.