When it comes to computer graphics, "deprecated/obscure" tech is the tech that is comprehensively documented from the ground up. There is some documentation about internals of the Raspberry Pi SoC and GPU, but sadly not enough to make it a compelling demoscene target.

I'm not saying you should. Enjoy your free time. I just think it's weird to shame people that care more by implying they have too much time on their hands. Everyone has a level of caring that's appropriate for them.

There's a lot of things you can learn from writing demos that is still incredibly valuable. I wouldn't expect 99.9% of developers to know those things, but if I saw it on a resume? That'd totally jump off the charts to me and I'd definitely want to interview that person.

Don't shame expertise just because you choose to spend your time differently.