I don't know about calypso, but if the calypso tradition is about improvising in a particular style rather than mainting continuity of particular songs, then I can see that the distinction would be meaningless. However the core of the traditions of the British Isles is this continuity and the way the music is passed on (although not necessarily unchanged). It is therefore useful to distinguish between those who are an integral part of this continuity and those who simply discovered the music at some stage of their lives, no matter how deeply they have subsequently immersed themselves in it. However, although it's a useful distinction I accept it is often endowed with a greater significance than is sometimes justified.