Blazkowicz
Legend
PS4 Pro games use checkerboard rendering to achieve 4k resolution whilst actually rendering sub-4k (close to usually, depending on title). PC will always render at the specified resolution.
Whether Forza @ 4k60 on Scorpio is using a similar rendering system or not I have no idea. Since there's a whole lot of horsepower in the scorpio, it may well be rendering at full 4k.
Why not use checkerboard rendering on PC then?, that'd be useful.
In fact, using a 1920x2160 rendering resolution with horizontal pixel doubling would be a useful option (as long as you don't use Microsoft Cleartype to render fonts in your game), well I imagine so.
Ages ago you could run Duke 3D in 320x400, although it was the one mode that had an issue with VESA 1.2 vs VESA 2.0 and was hard to get running. But if it ran it looked great while being very fast. Although maybe a raycaster engine benefited especially from vertical resolution.
So, if fake 4K is actually useful (esp. if you have high ppi) I hope the PC will eventually do it.
Otherwise I think what are missing on the PC are 4K high refresh displays. Also, on PC you have more freedom in what hardware you run and there could be 3200x1800 desktop monitors for a very high res but with much fewer pixels to render (30% less). Vendors don't seem yet interested though.