No idea why they are doing it, but I can say that on upgrading an old Windows machine, I discovered their financial software was completely non-functional and no windows emulation mode on the executable would work. I ended up running it in virtualbox in "seamless" mode in ubuntu+wine set to autolaunch the software... plus a windows share. For some reason that worked with no issues. The alternative would have been purchasing a half dozen upgrades and going through them one by one, with repeated database upgrades, for software that was working fine.

Probably not too much risk if the XP machine is isolated. There could also be licensing issues with upgrading, as well as unmaintained proprietary software.

Sure! I mostly use it for testing and finding the latest versions of software that still run without requiring SSE2 instructions (Athlon64, Pentium 4, etc.).

It's kind of like a functioning software museum - it has lots of old software and editors I used in the XP days, some games from around 2001, and some programming tools like Visual Studio/Basic, Perl, Python, Mingw/GitBash, Sublime Text, Ruby, etc. The only lang I haven't been able to run so far is NodeJS since it required SSE2 instructions very early on.

It has a 1300MHz Pentium 3 and 384MB of RAM, but with a PCI SATA controller and a modern SSD, it's pretty speedy and capable!

I once worked at a job that had a couple dusty old Windows 98 machines, because it was the last version of Windows supported by the control software for their expensive machine.