... and don't forget, ol' man Bach was a coffee-house musician. Yeah, that's right; the counterpoint crowd used to have fugue throwdowns at the local java joint; he who improvised the funkiest fugue wins!
That's right again- classical musicians/composers IMPROVISING, imagine that!
I'm inclined to think that if Muddy met Mozart on musical territory, they'd have an almighty jam session (and steal a buncha each other's licks). Little Walter used to swipe stuff from jazz horn players on the harmonica; think he couldn't have done likewise with Beethoven? Sure he could! (They call it a "Mississippi saxophone" for a reason.)
NB: Paganini was also an awesome guitarist. Once read an account (was it in Guitar Player?) by a contemporary who'd gone to whatever city to see the Maestro fiddle; strolling about the town the day of the show, he encounters a wandering minstrel playing his guitar with such skill as to have a growing crowd following him about. Eventually, the Mystery Picker gave them all the slip... That evening, when the curtain goes up, the great Paganini steps forth, and- guess who?
So Charlie Daniels would have his hands full, you betcha.