I don't see any evidence to support the assertion that this is the exception rather than the rule. My searching has only shown evidence to the contrary, that various fiddling and workarounds need to be done to get old apps working properly in Windows 10. Even moreso if you want to use some of the newer features they're promoting, like tablet mode or high-DPI. Legacy apps just don't magically work in those situations. Here is another source for this directly from MS, where various workarounds are suggested:
https://support.microsoft.com/en-us/help/3025083. Again I am not a windows user and I'm just going off of web searches so if you have some other evidence then please tell me. I just simply do not believe that MS has some kind of magical solution for perfect backwards compatibility. Supporting that stuff continues to take up engineering time and they will also gladly charge you an arm and a leg if you insist on needing it.
>In the Linux world, the community is pretty actively hostile to people simply wanting to run software not in the repo
This is wrong. Supporting software that is not in the repo has been the primary reason for adoption of containers, and also other similar things like flatpak and snap. The only difference with these is that the upstream distro cannot possibly support them because it goes outside their scope, so you have to get support from somewhere else.