What I'll for convenience call the Calt/Wald myth, the myth that we don't have evidence that blues music arose among folk performers, is not something that lucky people about Archie Green's age had their time wasted with back in the good/bad old days. Green knew that Elbert Bowman heard a variant of "K.C. Moan" about 7 years before 1912, and wrote that he did in his fine book published 43 years ago.

The Calt/Wald myth is apparently being swallowed about whole since 2004 by some writers, such as
Vic Hobson in his largely valuable "Reengaging Blues Narratives," 2008
David Roberston in his underwhelming 2009 book about W.C. Handy
Karl Hagstrom Miller in his 2010 book that Paul Garon rightly called "fatally flawed." Hagstrom Miller goes whole hog with his ignorant Waldisms: "Reimagining Pop Tunes As Folk Songs: The Ascension Of The Folkloric Paradigm," etc.

Oh, Hagstrom Miller misrepresents what's on pp. 149-150 of Odum and Johnson 1925 on his pp. 256-257 (par for the course with Hagstrom Miller), so looks like maybe Wald has read Hagstrom Miller. That's pretty much Hagstrom Miller's trip, asserting that people like Handy and Odum changed their stories about things (without adequate evidence that they did in the ways he claims), and pretending that if they had that would somehow prove a lot.

The reason the likes of Howard Odum, E.C. Perrow, W.C. Handy, and Perry Bradford thought the likes of black railroad workers singing a variant of "K.C. Moan" within Elbert Bowman's earshot by 1905 were within a "folkloric paradigm" was they were.