We seem to be getting close to the heart of the matter. For folk believers The Process is an irreducible creed - if you don't believe it, don't bother turning up. For the rest the process is either unimportant or misplaced.

I would suggest that songs were not grown evenly, that individual craftsmen were responsible for the major themes and verses altered, tweaked for local conditions and with time. They may even be formulaic for historical reasons with the template lasting for centuries. That is a historical certaintly based on a working knowledge of folklore and in no way diminishes the songs. The problem arises when the songs take on polemical stature, when they become a tribute to 'all those gone before'. They certainly do service to all who've sang them but that's not really what we mean, is it? The claim is something called The People took ownership by re-designing them or performing them in some way that made the originator less significant. That the changes were proprietorial and ownership became common.
I'm not predisposed to assign sole authorship to artistic texts where it isn't warranted - auteur theory in film, the idea of an artist-director transcending the restraints of the system to make a personal statement is largely bunk (for reasons I'm happy to explore if anyone cares), so positing genius where it's not appropriate is not my bag.

Nevertheless The People carries disproportionate weight and far too much emotional baggage to explain what's going on as an authorship and dissemination process. Historical anonymity has provided the vacuum for those so inclined to fill with idealism. The pleasures of the text for me are in no way altered by knowing the original work was largely or barely altered from the hand that originally formed it. There is a world of interest to be derived from the songs that takes no account of whether time and The People delivered them in their current form or not.

When Believers understand that enjoyment and understanding does not rest on that one notion, the polemical flames will die.