Really theres two sorts of folk festivals - the ones that are about booking big name guests, and ones that are a sort of community effort.
The second type has to reflect what the locals want, and generally it depends on strong minded local individuals who pragmatically do what they can.
The first type has got kudos for those artists deemed important enough to rate one of these prestige bookings. But in a way its a symbiotic thing. Really it depends on how active those artists and their agents/record companies are. I think it behoves them to at least mention the gig on their gig listing, maybe for the less popular artists - e-mailing a press kit to local press and folk programmes, if there are any left. Costs nothing except the effort these days. No postage costs etc as there used to be. If you have a following - they shoulsd at least have the option not to come.