Why are 2K and 4K (High Resolution) Scalings still a problem in both Windows and MacOS ?

MacOS

1. MacOS is scaling the whole system with actual display resolution based scaling. Not OS UI level scaling
Apple's solution is to just change the actual resolution output to the screen, resulting in a fuzzy / interpolated (GPU intensive) output

2. It is either native 4K where the OS text and icons are way too small or the pixel-doubled 2K/1080P where it looks like a large-print edition. UI elements are too big
However, 4K or higher display you cannot really use them at native resolution because the text is too small.

3. Except for the native or 2x resolution, all other options look blurry and GPU consuming
With it, except 2x resolution, all downscaling option means poorer performance (GPU gets under heavy load, more input lag is noticeable) and text is less sharp that it should be.

4. Scaling down from 4K display to another resolution causes more work for the GPU since it is compressing everything on the screen. 4K is demanding on many video cards

5. Once connected to a 4k external monitor, even MacBook Pro 16 inch runs very hot without any heavy task if applying scaling. It is not usable

6. 4K at 27 inch requires some kind of interpolated scaling as menu items and text are displayed too small natively at 27 inch display

7. 4K native even at 32" is really tough on the eyes.

8. Changing Scaling factor is not changing the resolution. Regardless of the scale factor Mac always sends 3840x2160 pixels per frame.

9. If you are scaling a 4K monitor to 200%, it is effectively the same as a FullHD 1920x1080p same inches display as the 4K monitor

10. The Larger Text option only makes the screen on the Mac lose all real estate.

11. If you have it scaled to have larger text and go to watch a 4k video on youtube, you not really watching in 4k anymore. In other words, is it essentially just acting exactly the same as a 2k monitor would. If you have it scaled to 2k it would act like a 2K Retina display

12. Having a 4k 27" display and using the 1440p scaling option in macOS to make the UI a comfortable size. However, with that setting, a 3840 x 2160 image in Photoshop is no longer the correct size when viewed at 100% zoom; it should fill the entire screen but instead is much smaller. While quality is not affected, it is annoying to have 100% zoom not equal 100% size


Windows
1. Windows is scaling at apps level with application based scaling

2. 4K displays improve productivity for the most part but if you run them on Windows, chance is quite high that you will run into display issues with certain programs, unless you only run UWP apps and native apps.

3. The scaling is still wonky and some apps behave differently. If you play games at a lower resolution and come back to desktop it can really mess things up.

4. Probably the biggest issue that users who work on 4K monitors will run into is that many Win32 programs don't support high display resolutions. While you can still run these programs, you will notice that text and information is presented in barely readable form

5. Problem is since there is no global setting that you can tweak, you are left with doing so for every program that you run on the system.
Even worse, some programs, especially older programs that are not updated anymore, may not offer these settings at all. You could use the on-screen magnifier when working with those programs but that is not really a solution.

6. But tiny text and interface elements is just part of the problem. If you run Windows 10 on multiple displays, you may notice blurry text, elements that look out of size, or elements that look fuzzy.