Many early folklorists seemed to prefer notating songs as they heard them and the importance of recording them had to argued for. Percy Grainger and Bela Bartok were among the first to travel with their "long horned Edison" wax cylinder machine to record the singers and musicians they hunted out. Grainger made a very good argument for recording explaining that it was impossible to write down all the variation inherent in folk music without listening carefully for a dozen times or so. A century later we can still listen as they did.

There is no argument that modern singers with modern studios can also do great justice to the old songs, just as there is no doubt they can be performed badly. But it's through the great collectors of the last century that we have such a wealth of material from so many cultures to work with.

I think most peoeple agree that learning from a recording is somehow closer to the original oral tradition we hear so much about, however failing a field recording there are also hundreds of songs that have been "revived" because someone at sometime treasured them enough to wrote them down!