Harvey,
You still don't acknowledge your confusion between bit depth and dynamic range which concerns me because you apparently teach this to others.
If you feel that someone who corrects your incorrect statements to be disparaging I have no control over that.
FWIW, there are no MTF charts at my site; so that confuses me.

Without quote marks it was hard to tell.
To me it looked like a long quote. Perhaps you were quoting yourself.

I didn't read this through initially because of numerous problems I saw as I scanned it.
Now I see one that mostly it's one very wrong concept repeated over and over.

Dynamic range is never expressed as "bit-depth".
In photography it's typically stops or Exposure Value (EV) and sometimes dB (decibels).
I cannot recall a camera that lists dynamic range in the tech specs.

Continued confusion about bit-depth and how it related to dynamic range.
If you intend to talk about "gray levels" then you're talking about tonal range not dynamic range.

More on bit-depth.
I'm unaware of any consumer camera with a bit-depth of less than 8.

Even more on bit-depth. And confusion with tonal range.
FWIW, 16-bit sensors have been around for a while.

Still following the fundamentally wrong concept of confusing bit-depth with dynamic range.

Right.

Actually that's demoasicing as well as other things like the power function and tone curve.
Quantization is what happens when the Analog to Digital Converter (ADC) converted the analog voltage to a discrete integer value. Perhaps you consider the reduction to 8-bits as a form of quantization.

It was a long post where you quoted material that at length.
Since you didn't author it I see no point in debating it with you.
I simply caution you and others to pay no attention to it.

Not worth the read considering that some of it is flatly wrong.

However, that is not photographically true.

I've never seen a clear statement of what type of dynamic range they are using.
So these values are of limited usefulness since you can't know if you're comparing "apples to apples"

I think it's described in the Further Reading but Low Light ISO is the ISO setting at which you get a PDR of 6.5 and Low Light EV is that ISO expressed as stops which is better for comparisons.

You may not realize this but the term "dynamic range" is ambiguous in this context.

Dynamic range is a generic term that is a logarithm of the ratio of a high value and a low value.
In photography that logarithm is usually base 2 (EV or stops).
Sometimes it's base 10 (dB or decibels, for example audio specs).

The high value is the "brightest" signal that can be recorded.
But there are some fine points regarding linearity and where the Analog to Digital Converter (ADC) clips which we will ignore.

The low value is not always the same thing.

I call the dynamic range of an individual pixel on the sensor Engineering Dynamic Range (EDR).
"Engineering" because this is the type of value you might find on a sensor specification sheet.
The low value in this case is read noise. Read noise is the standard deviation of the signal recorded in the absence of light.

DxOMark screen dynamic range is EDR.

DxOMark print dyanmic range (also Landscape score) is EDR that has been normalized as if the sensor is 8MP

PhotonsToPhotos Photographic Dynamic Range (PDR) uses a different criteria to establish the low value.
That criteria incorporates the Circle Of Confusion (COC), standard viewing conditions, and a minimum Signal to Noise Ratio (SNR).

Note that this is scene dynamic range as captured in the linear raw data.
After the power function (gamma) and a tone curve the dynamic range is compressed into a smaller range.
So it's entirely possible to take 14 stops of linear dynamic range and produce a 10 stop (for example) output image.

Also note that except for EDR these measures are independent of pixel size.
Pixel size has very little affect on dynamic range per unit area.

One reason I raise the ISO setting is when using flash in order to adjust the ratio of ambient to flash light; eg. avoiding black/dark background.

Another reason people raise the ISO setting is in astrophotography but that's a specialized case.

While it's true that setting a higher ISO can result in less light being collected this isn't the case when using, for example, manual mode.
The key thing is how much light is collected not whether that resulted from the ISO setting.

This is true (except for the "adds noise" part, gain doesn't add noise it just makes it more visible).

However, the noise floor is a function of the ISO setting; and extended low ISO settings have the same noise floor as the "true" ISO setting from which they are pulled.

Strictly speaking the sensitivity is the capacitance, so there is either one or two sensitivities, two being when it's a dual conversion gain pixel.

Adjusting amplification, either analog and/or digital doesn't change the sensitivity, only the lightness of the final image.

On the original post; extended low ISO settings have the same sensitivity as the base ISO setting (or sometimes even higher).

Don't confused pixel sensitivity with ISO speed and what happens with exposure (aperture and exposure time).

So, FWIW, the distinction between current and voltage is as follows.

A charge in electrons is accumulated in a capacitor in the pixel.
That charge is converted to a voltage in the pixel and that is the conversion gain; eg. milli-volts / electron
A dual conversion gain pixel has two different capacitance's switchable through a gate controlled by the firmware.

Downstream, on almost all cameras, this voltage goes through a programmable amplifier and is boosted, even at base ISO to prepare for the Analog to Digital Converter (ADC).

After the ADC you have Digital Numbers (DNs). Nikon usually scales the red and blue channels slightly while leaving the green alone. This is thought to be pre-conditioning that relates to white balance.

At higher ISO settings there can be scaling of all channels. I think this goes back to the programmable amplifier which has a maximum amplification; beyond that later digital scaling is necessary.

Hope this clarifies things.

Extended low ISO settings are accomplished by silent exposure compensation.
For example, on the Nikon D850 ISO 32 is exactly the same as ISO 64 with +1 exposure compensation.
This is why extended low ISO settings are more prone to highlight clipping.

It's also why measurements like 18% SNR appear higher, since more light was gathered the SNR increases at a given signal level. I don't consider these measurements useful for extended low ISO.

The best place to consult is DxOMark Measured ISO. Note that Measured ISO is the same for ISO 32 and ISO 64 for the Nikon D850

Another good place to consult, particularly if there are no DxOMark Measured ISO measurements is the PhotonsToPhotos Photographic Dynamic Range. Note the open circles in the attached chart are extended ISO settings which are 1 stop pulls from a the real ISO 1 stop higher.