The same market who made Apple the most profitable tech company in history? Sure, Microsoft wanted to be cheap and ubiquitous. But that's how you become redundant. Apple had high pixel density before they doubled it with Retina and ended up with 5K and 6K displays. Who's gonna complain Apple's displays are too nice?
What you don't seem to understand is that "Microsoft" doesn't drive the Windows ecosystem.
They put high-DPI displays on their Surface products for years and years. So
they agree with you. They introduced lots of APIs (that developers probably don't use) for making scalable interfaces, so the nuts and bolts are there.
But what do you want them to do to actually drive adoption? Make Windows 12 unable to boot unless you have at least 200DPI on your primary monitor? If you do THAT, the market will just stick to Windows 11 until the end of time.
Microsoft does not decide what hardware is used in Windowsland; Dell, Lenovo, HP, and co, along with grumpy jaded corporate IT buyers with a ton of older software to support, do.
Lenovo, for example, happily offered an optional 3840x2160 4K screen in most of their business laptops. I suspect that less than 5% of their buyers picked that option.
So, again, what do you want them to do? Do you want Lenovo to say "oh, well, we'll ONLY offer the 4K screen that no one except Gudi on a Mac forum wants" even though it costs them $200 more? If all Lenovos have 4K screens and cost $200 more unnecessarily, then... congratulations, most of the market will buy Dells and HPs with normal resolution screens and $200 less.
Apple, in late 2013, can say "going forward, if you want a 15" Mac laptop, it will be retina whether you like it or not, so open up your wallet and you're getting a high-DPI screen." And then a few years later, they can do the same thing with the other screen sizes.