This just reveals Microsoft’s prioritization of UX consistency. Whatever the priority is, it’s not enough to overcome the perceived cost of creating consistency.
It also shows why Windows can be a strength: still runs almost everything anyone ever made for it.
Now, I completely understand if some third-party program developed twenty years ago looks inconsistently. I even understand if some recent third party tool also looks inconsistently. But here we're talking about the software that is shipped with Windows and it's created by Microsoft directly. These are examples from Edge, Explorer, Settings, etc. This is more than having a low priority for consistency, this is Microsoft not even considering the possibility of consistency.
I have not tried Windows 11. But I'm baffled to find that in Windows 10, Microsoft still ships parts of its own UI that are not high-dpi ready. They seem to have zero problem showing dialogs with scaled pixelated text.
MacOS couldn't be more opposite in this regard. Linux I also dislike for this reason.
It's expect you compile your own programs, but more often than not it'll fail if the project is abandoned for 5 years (purely anecdotal).
In contrast with the earlier comment about how poorly Apple fares on backcompat: they have twice (thrice, actually, counting 68k->PPC) successfully made breaking platform changes where old software kept working with no required intervention by users or even knowledge it was happening.
Not everyone has been happy with Apple’s deprecation strategy, but there’s no technical reason MS couldn’t use their subsystem prowess to gradually move old technologies out of the core OS into sandboxed environments.
The reason they don’t is partly cultural—the compatibility at all costs trope is real—but I think it’s mostly a combination of lack of motivation and a recognition that the ecosystem produces a lot of abandonware that would quickly show seams.
Shipping an OS where some bits of UI date back to Windows 3.1 is never going to lead to a seamless experience.