We can make blunt statements about the limits of audio, because output devices behave (largely) linearly and band-limited, and because human perception can be modeled accurately and is also band-limited.

You can't say the same about video. The output is an array of points, not even perfectly square or smooth, it is picked up by another array of receptors, and is non-linear. The limit being 1/60th degree is too blunt a rule of thumb. That's picking an arbitrary point on a curve showing how much better than guesswork a viewer is.

The screen isn't a perfect output source, and the viewer isn't a perfect receiver, and the combined effect is you can easily observe the difference of 2K vs 4K images at distances those graphs say you wouldn't. I can easily observe the difference where it says I shouldn't be able to, and I'm nowhere near perfect vision.

I would say pretty much everything in those graphs is off by a factor of 2.

The real benefit from 4k is actually HDR and the MUCH higher bitrate for video. The majority of streaming 4k is really low quality when compared to a normal bluray. Just because the resolution is big doesn't mean the picture quality is any better. Also a lot of 4k content is actually upscaled from 2k sources. http://realorfake4k.com/

That table is purely relative to the mass-market options and tries desperately to make a case for buying a TV in 2017 which only supports lower resolutions than were common a decade ago. Looking at you, "HD" in 720p.

The only reason for me to go to a newer TV at this point is for HDR.