The worst part is that third party solutions (eg BetterDisplay) work. So Apple could find this if they wanted with ease. No clue why they’re so stubborn on it
Are you sure it works in a different way? I always thought Betterdisplay still showed you fractional scaling by downscaling from a much higher resolution. Well, I'd say I can still see the blurriness in the display when I pick a custom high dpi resolutnion from the list.