Why should this be regarded as an affectation? I've known songwriters get really upset if someone else sings one of their songs and doesn't credit it. Why shouldn't those who have done us the service of bearing part of the tradition (albeit most of them are now too dead to benefit from it directly) get a credit?

If I sing a song and say I got it "from the singing of Geoff Ling" I consider it implies a number of statements:
1) I did not personally collect it from him
2) a recording is available
3) I recommend the recording
4) it is a sufficiently different version from the one commonly sung to be worth commenting on
5) if you like it, you might want to consider listening to other recordings of him
6) if you have never heard of him, you might discretely want to catch me in the interval and ask who he was
7) I am at least going to make an attempt to sing it in the style of a member of a Suffolk traveller family rather than that of a country and western singer.

Quite an efficient use of 6 words, I would have thought.