It's kind of crazy how little these HiDPI screens have caught on among manufacturers. I really thought there would be a lot more 5K options right now, I'd personally love a larger 5K monitor like in 30-32" to replace my 24" 1920x1200 monitor.
I think the market (which includes PC users and gamers) has spoken and what it has said is that UHD (not even true 4k) is good enough, and 5k isn't worth the hassle caused by the additional bandwidth.
Several 5k displays from DELL, HP etc. have come and gone - and one assumes that if people had bought them in droves they wouldn't have "gone".
I've got a cheap 28in "4k" UHD sat next to my 5k iMac and the most obvious difference is that the colour reproduction isn't up to snuff - which has everything to do with the "cheap" and nothing to do with "4k." No, it's not quite as pin sharp as the 5k but it is very acceptable... and at 28" it is on the verge of being usable without scaling or pixel-doubling (if my eyeballs were 20 years younger and/or on a 30-32" screen I'd be running it at 1:1), whereas 5k wouldn't be.
5k is a niche for Mac users because MacOS - unlike Windows - has a fixed-size UI only available in 1x and 2x flavours, so it was a huge advantage that the 5k iMac was an exact pixel doubling of the original 1440p 27" iMac - whereas a 27" 4k display would give you a choice between eyestrain at x1, very chunky UI elements at x2 or non-integer scaling. In Windows - just crank up the scale to 150% on a 4k display and you're good. (To be fair, there are downsides on Windows with non-compliant apps and mixed-resolution multi screen setups - and modern iMacs have the grunt to handle 'scaled mode' smoothly).
Gamers (in general) would rather have a few extra FPS (and maybe a higher-refresh display) than a few more pixels, and the ability to plug in any old large-screen TV is a plus).
Serious graphics users will often stick to very expensive, colour calibrated displays that are only 1440p (let alone 4k) because colour accuracy can be more important than resolution (you can always zoom in to see detail, but if the colour information isn't there, you're stuffed).
The USP of 5k seems to be the ability to work on 1:1 4k content while still having space for controls, palettes etc... Or, just hang a cheap, large-screen TV off as a second screen and have a full-screen, distraction free preview instead... and
that's assuming you're not working with lower res/quality proxy files which wouldn't really benefit from being shown 1:1. That's where the
6k XDR - coupled with hardware that don't need no stinking proxies - starts to sound worth the money.
Then there's the slow uptake of DisplayPort 1.4 - without which, moving from 4k to 5k means either
two DP1.2 cables (and software support for MST displays) or Thunderbolt 3 (AFAIK TB 1/2 couldn't do 5k). Intel hasn't helped (AFAIK their iGPUs still don't support 1.4 and TB3 only added DP1.4 support fairly recently). My original feelings about 5k displays that relied on MST was that they wouldn't be long for this world, once true 5k DP1.4 displays appeared... Turns out I needn't have worried....
