No Dave, I disagree. It isn't the origins that matter, it is cultural sensitivies of the singer and listener that matter.

The issue of "origins" and the nationalist turf wars I mentioned, my experience has been that the origins debate tends to rise to the level of obsession with some nationalist oriented Anglo folkies, who are very keen to "prove" the origins of a song/tune as "English not Irish" or "English not Scottish". The obsession with whether a song/tune is English or Irish, or English or Scottish doesn't seem to matter near as much to the Irish and Scottish folkies.

As an American, I've also been involved in many US cultures' trad music communities, and I have to say, from the perspective of someone familiar with the music traditions both sides the pond, nobody can beat the English tendency/obsession with identifying nationalist origins to songs (to "prove" they belong to English). Perhaps that is because the English no longer have much of an indigenous living tradition, I dunno.