"For me, the benefits or otherwise of adding an instrument are to be found in the series of albums issued by Folktrax which have dubbed-on accompaniments."

It's not fair to judge the merits of accompaniments by this outrageously insensitive practice. Overdubs are difficult even for the most talented and sensitive musician, let alone when added to a vocal track recorded at a different time with no thought to the future provision of accompaniment. Accompanying a singer is a hard job even when you're sitting right beside them. Self-accompaniment at least offers the opportunity to have voice and instrument working in synchrony, harmony and sympathy.