Trying to discuss the term "traditionalist singer" without having any stated definition is rather like plaiting fog.
Taking Ray as an example; he has a large repertoire of songs including:
•        Traditional ballads
•        Music hall songs
•        Songs from Yorkshire
•        Modern songs (written within the last 10 years)
The subject matter is many and varied including in no particular order:
Murder, sex, drinking( beer and spirits), mining, tobacco, Yorkshire, prostitution, sailors, pregnancy, etc. etc.
Ray usually sings unaccompanied but does sometimes play the concertina.
Thus we may conclude a "traditionalist singer" can sing anything provided it is mainly unaccompanied.
A little facetious I know, but without defining terms, and slightly flawed logic, this is where we end up.