"My own line is a mile wide and isn't black, but many shades of gray"

I repeat, that is the point.

Of course I can hear the difference between an unaccompanied traditional ballad and say "The Bands Played Waltzing Matilda" (as a contemporary example) that's easy, they're extremes. But there is a whole lot of stuff in between these where drawing sharp distinctions as to the STYLE of the song is more difficult.