This was suggested by the "three chord tricks" thread, but maybe ought to be separate.

In that thread, several posters were suggesting alternate voicings for simple guitar chords as a means of creating variety. It occurred to me that I probably wouldn't be able to hear that variety, and neither would most listeners; its real audience was the player alone. In fact it occurred to me that this might be a lot more general: what non-guitarists hear in a guitar accompaniment is mostly texture and rhythm. Even the basic chord isn't usually very important. In folk music harmony is generally "non-functional", i.e. it isn't the harmonic progressions that are driving the development of the piece - they follow the tune. And any number of alternatives follow it equally well, most of the time.

Which suggests two questions.

1. Has anybody every done a scientific study of whether harmonization makes a difference to typical folk material? (Introduce random variations of harmony under a fixed tune, and see if non-guitarist, non-musically-technical listeners either notice the difference or have a preference).

2. What examples can anyone come up with where the harmonization is the distinctive and important feature of a particular arrangement of a folk tune - a particular harmonic effect that absolutely anyone would notice, and which made all the difference to how popular it became? How common are such examples?

One example much beloved of academic musicologists studying popular culture is Beatles songs. I am not convinced. To me, the tune does most of the work, and they communicate equally well in arrangements that ignore the original harmonization, so long as you retain something like the original texture and don't do anything too alien.