Another problem was that the MBPs of that generation had screen backlights with primaries that were some distance from the sRGB primaries ... especially the blue primary which was quite "purple". This caused some smaller (matrix / shaper?) profiles to map saturated blues to more purple tints on the screen. Note that the profile itself is correct, within the constraints of the screen's performance. A general fix was to go to larger patch counts and produce a larger, look up table based, profile.
So I've been doing more research on this. I notice that dispcalGUI has the following option: "Normally, profiles created by dispcalGUI only incorporate the colorimetric rendering intent, which means colors outside the display's gamut will be clipped to the next in-gamut color. LUT-type profiles can also have gamut mapping by implementing perceptual and/or saturation rendering intents." (I'm not exactly sure what this is doing under the hood, or what options dispcalGUI is passing to argyll).
The blue primary on my MacBook Pro display lies outside sRGB as best I can tell (it's kind of off to the side, but I'm not exactly sure how to read these graphs yet so I'm not sure if saying it's 'purple' is necessarily correct).
Would using a large LUT profile and enabling perceptual intent possibly solve or help address my blue-turns-purple issue?
______________________________________ it has a certain smooth-brained appeal