It is "all music" in the end. You are the one who has been unable to define "folk" for us. Folk music is plural, not singular, and you have so far failed to recognize that.

You accept your BRAND of what you grew up with as "FOLK MUSIC" - an apparently singular style based on your previous posts. You fail to realize that every nation has various folk styles that fit under the umbrella. Again, folk music is more like an encyclopedia set, not an individual volume.   Singer-songwriter, as defined by the contemporary folk community, is merely another entry.