About a decade ago discovered the dominant dialect area of my hometown (Tulsa, Oklahoma) was considered to be "(American) Southern Midlands", or "Southern Midlands American English". At the time this appeared to be considered a sub-dialect of American Midlands with some unique (perhaps SAE-related) features. The ones I particularly noticed in myself were the cot-caught and pin-pen mergers, and the use of "you all" for second person plural.
There used to be quite a lot of information on Wikipedia about this. But over the years, it seemed like there was less and less, it got moved around between pages, and now pretty much all signs of this existing as a dialect category have disappeared from the site. The only trace of its (former?) existence I can find now is a parenthetical mention, with no link, in the legend of a picture on their Midland American English page.
Wikipedia isn't alone though. I'm also having a lot of trouble finding info about it in other sources online. The only one I was able to find was from Robert Delaney's personal website, and at least some of the info in there appears to be 20 years old now. For instance, this map is dated 2000:
So my question is, has the idea of a coherent South Midland American English dialect area fallen out of favor? Should I quit telling people it exists?

(I also wonder if this is just Wikipedia editors being weird and arbitrary, tbh.)
– Leah Velleman Oct 01 '20 at 14:12