Sessions are for the musicians. People who go along to listen are forced to the margins and don't feel welcome. Naturally they want to participate, to become part of the circle and to get involved. They can't play a "real" instrument, but banging a drum must be easy, right? And there's lots of other would-be musicians doing the same thing. So they get a bodhran and join in.

Unfortunately the talented bodhran players faced with a crowd of thumpers usually pack up and go home.