use your proprietary software in the OS you are allowed to use. Not seeing the issue.
The OS they are able to use is Windows 10. They likely don't meet the TPM requirements to update to Windows 11(as if you'd wanna use it anyways); so when W10 goes EoL, they will be SoL(shit out of luck) on getting future security patches. Which is y'know, bad, especially on the machine you do actual work on.
In the case of business's, liability reasons, real and imagined, mostly prevent just "switching" OS's freely.
In the case of home users, think of how many people you know that have a windows computer. Now how many of those people can you confidently say could install ANY OS, let alone handle setting up Linux or bypassing TPM requirements for W11?
Personally, out of the hundreds of people I know with a windows computer, I can count on my fingers how many I'm confident in being able to install an OS. Most people are really not tech savvy. They will just ride it out with no security patches until it becomes Jenn's laptop from the IT Crowd, and then they'll chuck it in the garbage.