<- How highly would one rate a blues shouter or a cowboy singer attempting an a capella rendition of, say, "She Moved Through the Fair"?->

Now some people would accuse Peter Bellamy of doing that!

Going back to what Leadfingers was saying about

<- the steady chords of a basic guitar accompaniment effectively kills the song ->

there are/were some folk rock bands that manage(d) to do that - one in particular applied the "Status Quo" approach, shoehorning 6/8 or notionally 6/8 (damn these trad singers!) unphrased songs into 4/4 head bangers. Until guitar players start experimenting with the style of finger style playing that lends itself to unphrased songs (Carthy, Simpson and Foster being examples), just one simple stroke of the correct chord leaving it to ring over the melody works - a bit like playing sustained chords on a concertina (or similar).

I still maintain that had a plentiful supply of affordable instruments and time to play them had been available to the trad singers, they would not have shirked from using them in their leisure time. Songs of the workplace are a different thing.