Doesn't that disqualify them from being FOLK musicians?

New songs are new songs, even if they're sung in a folk style, non-amplified, whatever. Nothing wrong with them, but they're not subject to the "Folk Process."

Inspiration from folk songs, using folk songs as a context, this is a viable way to create new songs. But they are new songs.

It is possible to do several things very well: perform the old songs, and write new songs. It's also helpful if your audience can appreciate the distinctions and not hold it against the performer/writer for being able to do both.

SRS