No, Grimmy, the 'academics' haven't missed what Williams (or Hardy, or Clare, or any number of other people) wrote. It isn't 'academics' who try to tell people what instruments they should or shouldn't play in particular contexts. It is (1) other musicians and (2) organisations like Comhaltas in Ireland and the Mod in Scotland; neither of which are academic institutions. I'm not aware of any organisation in England that formulates rules of that sort; but then, we don't go in for formal competitions that much, and it is formal competitions that require rules. Such rules don't necessarily reflect actual 'real world' practice; Comhaltas and the Mod (and doubtless other similar organisations) recognise this, but they have their own ideas about what is or isn't appropriate and, naturally, the rules they set for their competitions reflect that.

That has nothing at all to do with the 'academics' who some round here love so much to demonise. If people misinterpret what others have written, that is not the fault of 'academics'. Alfred Williams, for instance (not an 'academic', but an authority in his way), when writing in 1923 of the disappearance of the church bands, did not at any point suggest that they ever accompanied folk singing; merely that they did not play only in church. Perhaps they provided accompaniment at times; perhaps they didn't. Grimmy has assumed that they must have, and cited Williams, incorrectly, as his (or her) authority.

As I said, the 'academics' haven't missed the reference; they have, on the whole, managed to avoid drawing false conclusions from it.