I would call Bruce Olsen a collector and suggest that his contributions to the cat have been outstanding. Often in order to make the most of a song it helps to know the background and collectors have often preserved this material along with the song. I would refer anyone to the Spancil Hill thread and use that as an example of material to be 'collected' along with the song.
I am not sure that I understand the comment re English folk songs, I've got shelves full of Irish and Scottish collections most of them old.
If collecting folk music/song preserves it keep collecting. I would suggest it's the pedantic users that are the problem not the collections or collectors. That's my penn'orth.
regards Baz