Sorry if you've misunderstood what I'm saying, and I think you have.I am delighted for the success of people like Martin Carthy and I wish that there were a lot more examples like him. I don't think there are too many. Even in the case of MC, I think many outside the immediate folk world would be asking Martin Who? (I don't mean any offence to the great man by that, I just think its true).
But there are a lot of people who have made enormous contributions to folk music who have never strayed much past their local pub, and these people are also successful, but not in the commercial terms that you are speaking of. Nothing wrong with that either.
What I am trying to say is that if a group of people want to play a particular style of music together, for their own amusement, there's no harm in that. Its how folk music started in the first place, and how its been continuing to happen, even after folk music was no longer all that fashionable after the 60s folk boom. If people want to take that and share it with the rest of the world that's fine too, but often somewhere in the middle of that the music biz takes over - and a lot gets lost in the translation.
Give me a little session in the corner of a pub over a big concert hall any day.