What, exactly, is the calculation you use to determine Photographic DR? Or is the calculation simply: "Shoot a step wedge and judge visually whether you have X stops or Y stops of DR?"
That's generally good enough, yes, though you're welcome to evaluate the shot with instruments.
There is not
a magic formula which allows you to translate engineering SNR for a sensel into photographic dynamic range for an entire digital camera. That seems to be what you are looking for and it does not exist. There are multiple reasons for this, not the least of which is that photographic DR is evaluated for a 2 dimensional light sensitive material with many imaging elements (sensels or grains), and is not based on a single element. If you applied an "engineering" definition of DR, or SNR, to photographic film you would conclude it has 1 stop because at the level of a single grain you would find either silver or clear base and nothing in between. (Ironic that digital cameras are analog at the sensel and film is "digital" at the grain.)
There are other reasons, but the point is looking at sensel SNR...even though it's related...gives a false impression. But just because there is no simple formula to translate sensel SNR into DR does not mean that DR is arbitrary or subjective.
In every single one of those pages you linked, including the book "The Negative" by Ansel (which I own, BTW), no one actually DEFINES what "Photographic DR" is.
Luminance range between black and white. (For the nth time.)
As for Ken Rockwell: "In photography, dynamic range is the difference between the lightest light and darkest dark which can be seen in a photo." Bingo.
I do not believe there is a single objective definition of Photographic DR.
Saying this after the references I've provided is...embarrassing. You're arguing to argue, not discussing to learn.
It's just an arbitrary term, and it seems to be redefined at will.
Every source I linked has the same definition even if they call it by another name (i.e. luminance range). I'm not aware of any other definition in photography.
I am calling into question the validity of using the old film-based Zone system to describe dynamic range in digital image sensors. Film had no readout system! In film, dynamic range was limited only by the amount of grain, which means it effectively behaved like an "ideal sensor"...the only source of noise was photon shot noise, inherent in the image resolved by the lens itself.
Grain irregularity was itself noise.
I cut a lot from your post where you're theorizing. Observe, then theorize.