I think the current myth is this thread has an identifiable and/or measurable subject. Myth-delta-blues or what?

Myth?
The thread title says we were done before we started.

Delta?
Why bother with any other definition than Lomax's? And then ignore it. Three great circus/minstrelsy producing dynasties of the 19th century, Rice, Robinson and Stickney all kept one foot in Cincinnati and the other in New Orleans. Why (other than Alan Lomax's personal outlook on life) would any one section of the river between be culturally isolated from any other during those decades of touring?

Blues?
It's not a static definition and revisions are both retrospective and obsolescent even as they are made.
"A blue note is a sour note....It's a discord-a harmonic discord. The blues are never written into music, but are interpolated by the piano player or other players. They aren't new. They are just reborn into popularity. They started in the south half a century ago and are the interpolations of darkies originally. The trade name for them is "jazz."
Gordon Seagrove, Chicago Tribune, 11 July 1915.

Joe: "Have you ever been there?"
Hoot: "...I doubt if he has ever left the reading room of his public library.... Perhaps he will clarify things by informing us what his qualifications and experience are. I don't ever recall coming across his name anywhere in my years of collecting, listening and reading."
Joe: "Joseph, don't take offense."
Me: [face palm]

It ain't the blues but I lived in the islands longer than the Lomax and Charters Bahamian summer vacations combined (200x.) As far as my family history goes it's not even close. Lomax produced a complete fabrication of static cultural isolation where none existed in the least. (My father honeymooned his 1st wife on Cat Cay the year before Lomax's so-called discoveries.)

The recently departed 'expert' Charters spent pretty much the entire summer of '58 behaving like a Mudcat troll. A real cool jerk and proud of it too. Zero respect for local customs and manners on both islands, NP & Andros.

I can think of no reason why the same 'methodology' applied to the elsewhere would produce better results. Keep the 'blues' recordings, as curios only. Bin the liner notes, books and 'facts' for the great steaming pile-o-drek they are.