ActuallyI suppose any instrument can be played "blind" when the player is good enough to where he/she can close the eyes and just groove. But the harmonica is one that doesn't even give the "learner" a "corner of the eye glimpse" of it.
I'm no flute player, but I've notice that I can see a lot more of my flute that I ever saw of my harmonicas. I actually have a student flute hanging on my office wall as a decoration. It's all I can do to get a sound out of the silly thing, and I'm totally confused about the buttons.
I remember taking it to church once and handing it tthe flute player on our worship team, and was flabbergasted to actually hear real music come out of the thing.