"It's self evident that fine folk songs are written by master craftsmen."
No it isn't, or if it is, provide your evidence...whoops - you don't do eviidence, do you - rather, you much prefer to make unsubstantiated statements from your armchair - much safer that way.
The bulk of folk songs sung today (with the exception of the ballads) are 19th century; not too long ago in the grand plan, yet researchers have failed too come up with 1 composer of the standard repertoire.
In an area like West Clare, which had a large repertoire of ballads, native-Irish, Anglo-Irish and local songs composed within the lifetimes of the singers, researchers have failed to come up with 1 author; with the exception of a local poet in the 1920s who contributed 2 songs to the town repertoire (from a published collection). In spite of the quality and size of the local song repertoire no 'master craftsman' has ever been identified.
Travellers sang songs which must have been made within 5 or ten years of their being recorded, yet failed to identify 1 songmaker.
Researchers, particularly American scholars, Bronson included, have combed the collections and again have failed to do so.
Maybe they were looking in the wrong place - perhaps they should have stayed at home and stared up at the ceiling till the answer came to them, as you appear to have done.
It is nonsensical (and not a little arrogant) that people who have been involved in a music they recognise as folk, for many years should be asked to abandon everything they know on the word of a pair of clowns who make vaccuuous statements on the basis of.... well, nothing.
                                              WHERE IS YOUR EVIDENCE?
Jim Carroll