"Is folk self-regulating or decided from above?" - part of my original question.

On the basis of attending festivals I'd say folk was entirely self regulating in an organic way. Balladeers and bands with electric guitars doing folk-rock rub along prefectly well, as do bright eyed audience members with gnarly gentlemen with Santa Claus beards. I can only recall seeing one fight at a folk event and suspect it was a domestic; fear and loathing is notable by its absence.

For clubs I can't speak, but if some Mudcat posts are a guide 1954 defined tradition is nearer to the surface as a booking policy, though it seems other clubs follow a wider folk-acoustic-roots-world music agenda. The main part of the question asks whether other kinds of music have formal frameworks that in any way efect what's played. It seems they do and I'm interested to know of others.