Are there truly insurmountable reasons why an ancient os can't be used, even a closed source os like Windows, that couldn't be worked around by building some kind of compatibility layer, given infinite effort and resources?
If you really wanted, you should be able to use any old version of Windows or whatever in VirtualBox or VMware or under Qemu/KVM. Probably have limits around screen resolution - I don’t think you could coax Windows 3.11 or 95 to do fulscreen at 3480x2160 - but if you just want to get it going, you could.
A few years ago I nearly got the first Red Hat Linux release going under KVM. I imagine someone who knows it better than I could succeed.
But the older the OS, the harder it's going to be to get anything modern working on it. And people do have finite effort and resources.
And frankly, it's just not a great idea anyways. For all the complaints, modern Windows is heaps better than its older counterparts for usage today. It's much better at utilizing modern CPUs, SSDs, GPUs, etc. It has (if imperfect) up to date security measures. More or less everything is out-of-the-box compatible with it. I can't even remember the last time I had something break and it was actually on the Windows end and not an application running on top of it that was the problem.
Things like kernelEx did exactly that. There’s also HX for MS-DOS. Thing is, as fewer and fewer people use the OS for which compatibility is intended, the translation systems fall into disrepair.
