"discussing... 'Academic collectors were particularly slow to associate the blues with folklore'" "Thought I Heard That K.C. Whistle Blow" e.g. falls within what we call blues songs. Odum associated that blues song with folklore as of 1911 (and as of 1908).

"was later replaced by a 'folkloric" Odum was collecting folk music in 1905-1908 and thought he was collecting folk music in 1905-1908.

"people you call 'folklorists'" They were folklorists.

"later on, this degenerate view was replaced by a view that 'folk' was something communally created" I don't recommend taking Hagstrom Miller identifying supposed trends seriously.* Lots of people thought lots of things about folk music during e.g. 1880 to 1929.

*If you want to understand why, you can ask yourself whether there is really anything in my review of his book, in which I point out outrageous claims he made, outrageously wrong, that is incorrect. (Howard Odum and John Lomax were folklorists, e.g., so that wouldn't be it.)