In any case, Windows is just using a scaling feature. But when you scale, you are losing workspace in exchange for sharpness.

When 4 physical pixels translates to 1 logical pixel, you've actually lost 3 pixels of potential real estate on a screen size where your eyes can actually discern those pixels.

On a 15" 4K monitor, losing that real estate is not a big deal, because >90% of people can't easily read or see anything scaled at 1:1 on a screen that size. When you scale that screen at 200%, you're basically using a 1080p screen with sharper text. You don't gain any real estate at all from the higher resolution.

On a 40" 4K screen, it's a whole other story. The text may not be sharp, but you can have way more windows open on that screen, which makes it easier to multitask. It's like having a grid of 2x2 20" 1080p screens.

-addendum - my visual limit is 1080p @ 1:1 on a ~14" screen, which is why I am fine with no scaling on my 4K 27" screens.