He wasn't joking! That's certainly one valid way of looking at the question.

Brian, my own experience of Bert's FSE exactly matches yours.

In answer to Matt, many of these topics have been studied in academic works (mostly US or continental) and perhaps it would be useful to start making a comprehensive bibliography of these.

As the vast majority of the ballads we now call folk songs were shaped by those who wrote the broadsides we should look more closely at the characteristics of these.