I think you misunderstand what's happening with macOS resolution scaling. What you're describing is assets being rendered down and getting blurry; but this doesn't happen to text because text is vectorized. You're right that some assets like icons and such will be less sharp at 1.5x than 2x, because 2x will have an actual asset and 1.5x will have to be scaled down.

How does Windows fix this? I have used so many Win32 apps that are jus broken in one way or another on HiDPI displays, most shockingly Visual Studio, my experience of HiDPI on Windows is always worse.