I'm willing to bet that GUEST,Folklorist was in Ireland or the UK, not in America, when told of the unsuitability of the guitar for folk music.

I know that in the Irish/Celtic folk tradition, songs were traditionally sung unaccompanied, and even instrumental tunes were usually played without any chord structure, using "one-note-at-a-time" instruments like the fiddle and whistle. I know less about British traditions, but suspect that the history there is similar if not exactly the same.

The introduction of guitars, banjos, etc., into Irish "trad" music and similar repertoires is quite recent, very likely in response to the '60's American folk revival (which was heard, to some extent, around the world). The introduction of "chording" intruments into these traditions has generally required a thoughtful approach and good ear for modal scales to preserve the essential qualities of the original non-harmonic sound.

In the US, on the other hand, there is no similar tradition of music played without guitars and similar instruments. The banjo is an American invention, developed from earlier West African instruments, and has been part of the US folk heritage pretty much from the beginning; it probably played a role in the development of song structures that are usually built upon chords. The guitar is only a little newer, perhaps making its earliest appearances in areas originally colonized by Spain. In some American folk forms/traditions (notably the blues), guitar is probably the *original* instrument.

In the US, the *electric* guitar may have been newly introduced in the mid-20th century, but the basic acoustic box has been an essential American folk-music instrument for much longer than that.