> I can only assume they're intending to run this on something extremely ancient that would end up being less power efficient for the task.
I don't think I've owned anything PC-like that didn't have hardware OpenGL acceleration since the late 90s.
CRT simulation didn't run well on Intel iGPUs for a very long time. While they could run the effects, they couldn't run them fast enough. There was longstanding advice in the emulation scene to not bother using shaders unless you had a dGPU; that only changed around Sandy Bridge, where the performance became sufficient.
Even a Raspberry Pi can handle this stuff at low power consumption today.