Not sure if that's strictly true as we're dealing with dynamic control the whole time. In our version of Child #102: The Birth of Robin Hood (as featured on John Barleycorn Reborn Vol 1) for example the dymanics of the music are keyed into the events of the narrative, likewise in our other ballads, such as Diver Boy, we certainly stress a lot in there. This comes quite naturally to us as singers especially when we're singing together; in singarounds I agree things tend to level out rather but (generally) that's a matter of being heard. I don't think it's the genre - nor yet the makings of a rule - but I do agree that a lot of Traditional Folk Singers weren't trained as such, so maybe such considerations as dynamics aren't that important but you can't write it off altogether. In classical music the dynamics are as aspect of a composition, in Folk Song they're very much the choice of the performer & that's going to be different each time.

So - no rules, eh? Let us each rejoice in the freedom to do what suits us best on any given occasion.