"What do people use XP for these days?"
Hacking.
I currently have DX12 operating on XP-x64 (basically consumer 64-bit Win Server 2k3) with some minor hardware recognition issues. I have many modern games running this way. Many of them run much faster under XP than under their officially-supported OS (Win10+) which is an absolute shame.
That's interesting, how did you get that to work? I imagine you'd also need to somehow get device drivers for a newer graphics card to run (as well as for newer hardware in general if you don't want to be CPU bottlenecked). It seems like a lot of really cool work. Have you posted about this anywhere?
"That's interesting, how did you get that to work?"
Lots of registry modifications and .ini file modifications, and a huge chunk of help from someone who is currently making modern browsers and various modern software bits work under Windows98.
"I imagine you'd also need to somehow get device drivers for a newer graphics card to run"
That part is a bit more trivial thanks to unified driver architectures for GPUs. Not much more trivial, but a little.
"as well as for newer hardware in general if you don't want to be CPU bottlenecked"
CPU is the primary issue I'm having, indeed. Chipset drivers are the second biggest issue.
"Have you posted about this anywhere?"
And have Microslop banging on my door with lawyers because I show how modern versions of AI-slop-coded Windows are actually slower than older versions coded by actual humans? I'm good on that one boss.