The unaccompanied singing voice is certainly one of the easier instruments to carry to gigs.
It is perhaps one of the more difficult to impress people with (she "just" sings is a common comment - is that "just" as in "merely"?)but that doesn't mean it can't be worked on and improved over time.
Is there some idea out there that you have to improve your instrument technique (guitar, concertina for example ) but not your singing technique. Maybe.
Harmony folk singing is IMHO one of the greatest sounds (is that unaccompanied?).