The 5500 XT would have qualified, too,
Might I interject, the 8GB version. I had it, no wimp at 1920x1200 for all the games I played and some were old, some were new, most of them I did what Frick described: Didn't even look at the settings.
The 4GB version of that card, I have my doubts. Before, I had the R9 280X (3GB) and some of the simulators I had would actually hit the vRAM barrier rather fast by 2016, other games were enough to slam the chip at 100% once some shading and occlusion were activated. The RX 5500 XT was within 5~15% performance above the R8 280X, albeit at some 150W less.
Otherwise I am agreeing with most of your points, although I see Frick's argument leaning towards the whole definition of a "set & forget" card being the base, adding resolution increase to the math, so what I end-up concluding is the existence of the unicorn "all-rounder, jack-of-all-trades, ace-of-none" for its supported life...and that was the 1080Ti that was most famous, I believe. But other contenders were the 8800 GT (G92), HD4870, HD5870, GTX580, R9 390, GTX970, 1060Ti imo.
Historically, that has been the card that when launched, people could be "comfortable" in their investment so that although expensive in the market range, it ran every contemporary game title with leeway for more, eventually more complex game engines in the supported card's life...assuming resolution did not change (this aspect has not been linear either in its evolution).
- The RX6400 (...) A $110 price (and low profile!) would be great.
Not going to happen while there are GT 1030s at the €100 price-point.
As for Hasmter's arguments, its the moment both camps decided that the next gen numbering wasn't going to match the previous at its performance AND price-points. So comparisons ran wide just before the crypto craze it and it sent already confusing segments into nightmare pricing. Then its everyone's understaning of their own expectations. Sure, a decade ago I didn't expect my HD 5770 (1GB) to do wonders, but I did ran all the games I threw at it at Medium and some at High, with a 1080p/60 screen. IIRC, at that time, aiming for 1080p playability was still...not the case, 1680x1050 was, while most displays were still 1024x768, 1280x800 or 1440x900.
Either consumers expectations raise or their demands, the market will have to comply to turn a profit. I think what both of you are concluding is that expectation has been all over the place and the demand has not been consistent, because of the various factors that existed for the last 6 years or so, but yes, this should not be an excuse for having a market segment "disappear" over the existing ones all raising themselves, imo. Even if just a bit.