Earlier quoted context omitted.
I didn’t miss it; it’s just not valid. (1) The HD800S is actually not as highly regarded as you may think on ASR because these issues do show up in the measurements and are pointed out in the review (did you read it?), but also (2) the HD800’s issues are indeed very much fixable with EQ, and I can confirm this subjectively with direct experience with my HD800S. I hope you’re not thinking I’m advocating a crude N-band…
You claim high-end audio is not subjective, but then bring up the Harman target. You're defeating your own point. As you know, the Harman target is a "mass market" pleasing option for average joe's. Its not the be all and end all of audio signatures. I am in the "bass head" camp, and I loathe it for a lot of the stuff I listen to. I'd take a JVC HA-SZ2000 over the HD 800s for my taste.
(1) We have an objective science that disambiguates and understands differences that are subjective versus universal preferences in speakers (to some reasonable threshold of population universality; e.g. maybe you find some 0.0000001% population that prefers horrible screeching noises added to any audio content, but arguing for this as an important dimension of subjective variability that we need to incorporate into hardware is I hope clearly absurd).
(2) The vast majority of subjective variability relates to differences in frequency response, which are extremely easy and cheap to adjust in software -- no need to cycle through many multi-thousand dollar headphones or speakers just in hopes of finding one that suits your preferred frequency response target.
(3) Almost every kind of imperfection that can't be corrected via frequency response tuning (e.g. undistorted SPL capability, THD, IMD, off-axis smoothness and similarity to on-axis for speakers, power handling and dynamic compression, etc.) turns out to be almost universally disliked versus when that imperfection does not exist.
(4) Once frequency response balance is factored out either via custom EQ or a "mass market" target curve (which for headphones is indeed more of a compromise, but for speakers is not even remotely a subjective matter, since there are mountains of scientific evidence over decades proving over and over again that the preferred anechoic frequency response for speakers is flat, i.e. the mathematically perfect identity function), which naturally yields a preferred in-room target curve of a smoothly declining slope -- very little (if any) subjective variability remains (e.g. bass boost or treble tilt to taste is one such example).
(5) To be clear, some subjective variability does remain, but it mostly relates to head fit and comfort (for headphones), and for speakers is much more nuanced and tends to relate to beam width and height differences. In both cases, the science is capable of examining these precisely, not in some kind of vague or hand-wavy woo woo sense. Lastly, there is always some need to make some coarse adjustments to bass and treble when listening to older recordings or recordings which were mastered to a non-neutral reference curve (as they should be, else it's impossible to ever reconstruct what was intended) -- but this is not so much a matter of listener preference as it is correcting for mixing/mastering errors in older or lower quality tracks.