Not to mention banjos, cornets, clarinets, saxophones and especially trombones. A trombone plays as in tune or out of tune as the musician playing it wants. The fact that they played blue notes before guitars started getting involved in the blues tells me that’s the way they wanted it to sound, not that they adapted their music to the badly made instruments of the day. W. C. Handy didn’t have a guitarist. Louis Armstrong started out the Hot Fives and Sevens with Johnny St. Cyr on a banjo - St. Cyr picked up the guitar much later.