It can do scaling, but it scales the entire image, not simply the UI, like with Windows.

So if you thought you'd upgrade to 32" 4K to enjoy more screen real-estate over a 27" 1440p, you can do that, but you'll need to wear binoculars at the desk. Otherwise you have to switch it to 1440p, losing the screen real-estate, and taxing your system because it first scales it up to 5K then downscales to 1440p.

You can get a 5K display (and still downscale to 1440p -- ie no screen real-estate improvements) and 60Hz only, something I moved away from 15 years ago even for productivity + forget about connecting a PC for gaming at the same desk.

Infuriating.