So the quantizing for the 212-point profile shown by Histogrammer is obviously a bad thing. The question is whether the quantizing is from Histogrammer not doing a linear interpolation between the profile TRC points (the ICC does specify to use linear interpolation between the points). We can’t check without access to the Histogrammer software source code.
What happens to the histogram when you use cctiff (cctiff) to convert from my V4 sRGB profile to the 212-point profile? What happens to the histogram when you do the same thing using LCMS’s tificc (Little-CMS/utils/tificc/tificc.c at master · mm2/Little-CMS · GitHub)? I guess it’s not possible to tell using Histogrammer, if Histogrammer indeed does not interpolate between the points? Maybe do a round-trip for each conversion back to my V4 version of sRGB, and then check using Histogrammer? Or maybe use Imagemagick to count the number of colors in the image “before” and “after” converting and/or after simply assigning the different versions of sRGB?
If a “failure to interpolate between the points” happens in various softwares, that alone is a reason to confine the use of “small” sRGB profiles to 8-bit images displayed on the web.
@saucecontrol - is your final version of the small sRGB profile available for download? If it was given in your Part 3, I didn’t see it, but I was scanning for the main lines of your argument, rather than for a download link.
Regarding your proposed values for the sRGB profile’s RGB XYZ tags, I see where you are going with your line of reasoning. Here’s my understanding so far, so please correct me if I misunderstand:
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It’s not enough to use the correct source and destination white points and the correct source xy values, and then “nudge” to get well-behaved primaries in the profile that is saved to disk.
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In addition, one must make sure the resulting primaries are invertible, to get back to the xy values in the spec.
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These invertible primaries - at least for the sRGB ICC profile - are actually in the sRGB specs and/or in the ICC’s recommendations for making an sRGB profile.
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No-one ever, anywhere, ever - including Graham Gill (my sRGB primaries match Graham Gill’s sRGB.icm by design), HP, and the ICC - has ever actually produced a correct sRGB ICC profile.
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And because of the way the source white point is calculated, all true V2 ICC profiles (including I presume AdobeRGB1998) that have ever been made for a color space with a D65 source white point - or at least the ones I included in my various surveys - all of these profiles have incorrect white point tags.
I haven’t had a hex editor installed on my system since iccXml was released, so first I want to install a hex editor (or maybe 3 or 4 hex editors 
), and then reread through your Part 3. So clarifications on where I might have misunderstood Part 3 are greatly appreciated. A link to your proposed replacement sRGB profile also would be nice!