True; though in some cases there is more to it than that. Every recording of The Rose of Allendale that I've ever heard, for example, is clearly derived from the Copper Family's rendering of it, not from the original song written by Jefferys and Nelson, which is significantly different musically. The Coppers credited the composers on their recording, but the majority of those who have since recorded arrangements of the Copper interpretation of it have lazily passed it off as "traditional", which is simply not true.

Three Score and Ten, though the writer is known, is also a bit more complicated, and in the form in which it was taken up -from oral sources- by the Revival probably should be considered traditional, though that is no excuse nowadays for failing to name the original writer, of course.