Many folk clubbers also go to festivals but clubs seldom seem to attract new interest from the bulk of the festival crowds although they might come along on a "one off basis" to see a particular act.

You'll also get many people attending festivals who are just there for the occasion or event and or not particularly interested in the music at all. they might just be there for the drink, camp site parties or whatever... even to create havoc. The clubs are probably better off without them.

Also, a festival will attract families which can be considered a good thing as many clubs are not geared up to accomodate these. So, there will be spouses, offspring, freinds, and even pets who will accompany the folkies themselves. They may or not be that interested in the music either.