Come to think about it, why is this BS?

Don't we have to know what folk is before we can say what the size of it's market is? Surely the issue as in the European Law definition of a market share is about cross-price elasticity of demand, or facility of substitution. (Translation for non-competition lawyers, does one talk about a monopoly in the market for fruit, or the market for bananas? At what point, if restrictive practices drive up the cost of bananas will people buy oranges or apples in stead).

If you take the views of Louis Armstrong (now we know why they called him Satchmo - he had a mouth bigger than was good for him) there is a large market for folk.

If you take the 1954 definition, then the music is community music and not part of the market place (to a large extent).