"Then logically that could apply to any piece of music."
It might, if that music is anonymous - most composed music isn't
The term 'Folk' identifies a specific section of the community anyway - that's why folk and traditional are two sides of the same coin
'Folk' as applied to the peoples' culture was agreed on in the 1830s tp identify lore, tales music, dance, song..... the creation of 'the lower orders - 'The People'
Jim Carroll