The underlying question in this thread is does the guitar interfere with traditional unaccomapanied singing? I think the answer is yes and no. The use of guitar in early American country music is often skilled, tasteful and does not interfere with the vocals. Does it interfere with Doc Watson's vocals? But then there is the early styles of singing such as Sean Nos and Appalachian balladry. Here, in the first case, a drone from the pipes or a rubato (out of rhythm) chordal harp-like accompaniment would work best and in the second case, a dulcimer or a rapid free-flowing banjo style in modal tuning works well.

The bottom line, does the guitarist have the knowledge of the musical style, the skill and the sensitivity to provide servicable accompaniments that enhance the singer?

Frank