I played harmonica in a coffee house trio in college. I was a long time trained musician (jazz piano) and i was really good friends with a couple guitar players. Even though i knew music very well, i couldn't contribute much because i had yet to learn guitar.
We got our hands on a beat up Epiphone 12 string with action high enough to use as a trampoline. Then we tuned it to an open C and i played slide on some songs where there were a minimum of minor chords.
If there were minor chords abundant, i'd play harmonica. The only problem i really had is that the way i bent notes was too aggressive or something and i used to bend the reeds so they would go out of tune. Sometimes i could open it up and straighten the reeds, but getting it back together so it doesn't leak air was harder than i thought.
After i learned guitar, i quit worrying too much about harp because i now had an instrument i could carry. Of course, later on when the electronics boom hit the music industry, i could get amazing sounds out of keyboards we could easily move from place to place. Good thing, too. At 90 to 100 gigs a year, moving a piano and a Hammond would have been a drag.