Yeah, but it's a slippery slope, because no program runs in complete isolation. Even on the simplest 8 bit machines where there is no OS to speak of, you are still benefitting from the capabilities of the hardware - generating sound and music with the C64's SID takes a lot less bytes (and still sounds much better) than trying to do something comparable with more primitive hardware like the PC speaker. That's probably also the reason why this demo uses MIDI.
if your OpenGL driver had a glDoACoolDemo(); function, you wouldn't be allowed to call it. But if you find that among the regular functions are some code blocks that just happen to form a cool demo, you can use them and take credit for your discovery...