Doug Chadwick asked a question earlier that needs answering:

'In the oral tradition, a song can change slowly and subtly as it passes down the line. As recording a song freezes that version in time, is there a danger that the very act of recording might remove a song from the oral tradition that the collector wants to preserve?'

To which I would reply: No more -in principle- than taking a photograph of a horse jumping over a hedge prevents that horse, or future horses, from doing the same thing in a slightly different way; neither, for that matter, does it prevent the hedge from continuing to grow. It helps us to understand the way horses do it, though (it was photography that made possible the analysis of how horses moved) and exactly the same is true of recording folk song from tradition; though there, I hope, the horse analogy will be allowed to end.

The commercial issuing of recordings does have a tendency to standardize, but that is another matter. In the case of song nowadays, it is usually arrangements made by revival performers that become the 'norm' among later revival performers. That is not to say that there isn't a tradition involved; just that it is a new tradition, and it doesn't work in quite the same way. It is important to make that distinction, not because one is less 'valid' than the other, but because they operate in different contexts, and it is only by understanding the context that we can appreciate what is happening and what has happened; and, in separating the two, draw (perhaps) useful conclusions.