I thought that might be the case.

Some festivals attract a more passive crowd, and some a more participative one. Big Session has tried to create a more participative vibe, but so far is a more passive festival - fewer players and fewer sessions. I don't think they do much in the way of adult workshops or events other than concerts, which is probably partly responsible. They also have the big oysterband presence and probably attract punters from the more commercial end of the folk scale.

Maybe the solution is to go with a group of friends and start your own session!