It's a mix of both. Musicians often want to seem like they didn't take lessons and don't have in-depth knowledge of music theory and old songs, but they often d

It's a mix of both. Musicians often want to seem like they didn't take lessons and don't have in-depth knowledge of music theory and old songs, but they often do (e.g., how many guitarists don't admit they took lessons and want to make it seem like they're just riffing but they mysteriously seem to hit the chord tones on the changes and manage to play in modes that work for a song). It's just not "cool" for a musician to be knowledgeable about music theory and history. I think every pursuit - not just music - is presented with a challenge once it's been around for a while, it's no longer new and unusual, and there exists a body of knowledge and history. It becomes a large task to learn from past performers and then try to innovate in your own way. Once a body of knowledge becomes large enough, it's a big life-consuming task just to get your head about the prior body of knowledge before you're able to go out on your own and attempt to innovate. I think the same thing is happening with rock. The same could be said for philosophy itself - philosophy used to be practical and applicable to everyday people (see Greeks and Stoics, for example). Now, it's largely confined to academia and extremely esoteric arguments among a cloistered elite.