That's a distinction that doesn't have to exist. If you don't insist on maximizing all windows, a single large monitor gives you more flexibility that multiple monitors with the same total screen area. E.g. for many applications 1080p is too wide to be effectively be used by a single window but too narrow to have two windows side by side. Dividing a 4K or screen by 3 is much better and also allows you to freely choose the window sizes. Some basic tiling support in your WM (either automatic or via shortcuts) is recommended ofc.

I use a 38" 3840x1600 monitor (= about 110 DPI) at 100% scaling and it works just fine for me at normal sitting distance. That's the same horizontal resolution as 4K and I don't think the missing 560 pixel rows would make much difference to how I would use it.