And many of the original intros, before the term "cracktro" was even coined and which predates demos (demos were standalone), would often reuse music from games

And many of the original intros, before the term "cracktro" was even coined and which predates demos (demos were standalone), would often reuse music from games and not music from other intros. So those plundering the digital high seas would not only remove copy protection and write an "intro" to both boast about it and show their coding skills, they'd also steal music from commercial games. And they were the OGs: the demoscene only came after the work (a bit shady of a work but a work nonetheless) of these pioneers.