Dunno about 'over the pond', but over here in li'l ol' England, unaccompanied singing is an artform in itself. By that I mean some songs were never meant to be accompanied, and to inflict accompaniment upon them would be putting the musician before the music!!

A prime example is the Sea Shanty - few shanties (except fo'c'sle shanties) would ever have been accompanied, because everyone involved was working.

'A capella' is not quite the same thing. Okay, by definition 'unaccompanied' and 'a capella' are the same, but I hope I have clarified the subtle distinction between songs done without accompaniment, and unaccompanied songs...