Jim ,they are excluding people, that is the problem.
just because a tradition was once some particular thing, e g unaccompanied, it does not have to remain unchanged, that is similiar to preserving something and not allowing it to alter, a healthy tradition can accept change and evolve.
yes, they are imposing it upon others they are preventing singers, and excluding singers from performing with accompanying instruments.
I have no problem if I am asked to do a night of unaccompanied singing in a singers club, but I dislike seeing good singers who wish to accompany their songs being told they cant use a guitar, as one irishman said to me recently, when told just this, in a singers club"Ihad enough of that sort of thing from the Christian brothers, telling us what we should and should not do"