you have to hand to led zepplin, in the 60's they made it possible for white suburban kids to listen to watered down black blues music performed by white british musicians without having to cross the color barrier themselves.
The Zep tracks that hooked us white kids in were
not the recycled blues songs. Tracks like Immigrant Song, Black Dog, whatever... there was no black blues act that had that sound.
Also note that black blues acts had no black kids in their audience by that time. If it wasn't for a few white kids who did cross the color barrier, as you call it, their careers woulda been over