Sometimes, "because it's possible" is all you need ;-)
But now, more seriously, it'd be fun to try to port it to different 6502-based computers. I've been looking for a good excuse to get myself an Apple III or a BBC Master and this seems like a great one. Not all of them will be able to have preemptive multitasking (interrupts aren't always convenient), but it'd still be fun.
Imagine that - in 2023 we could have software that runs unmodified on more than one 6502-based computer...
It provides some template configuration files describing different memory layouts. And provides common libraries for input/output.
There's also a LLVM fork for MOS: https://github.com/llvm-mos/llvm-mos
They've got some interesting hacks with ZeroPage memory and register allocation: https://llvm-mos.org/wiki/Code_generation_overview
Interesting if you geek out on that kind of research.