Well, Dave, first of all, Cahill doesn't fingerpick, and when you are playing a whole set of instrumentals, it really helps to introduce some variety into the accompaniment.That said, I am aware that there are flatpicking guitarists who are able to provide imaginative fiddle accompaniment. Jody Stecher springs to mind (backing Alasdair Fraser).
What Cahill does is not really flatpicking however, he simply provides a monotonous choppy downstroke chordal accompaniment, no runs, no counterpoint, no imagination, no lyricism,, and quite frankly, it pisses me off.
And while I am ranting, I would add that while living in Scotland, I noticed this style of accompaniment being adopted by some younger players. I have a feeling that it originated in the Shetlands, with the legendary Peerie Willie, who imitated the rhythm stle of the jazz players of the twenties and thirties and adapted it to the traditional music of the Shetlands.
Well, it just doesn't work, IMHO, and the sooner these young players learn to fingerpick, the better off the music will be. Hazel Wrigley, are you listening?
Murray