macOS works, ARM has support for years; for many projects all you need to do is pass in the flags requesting support for both and they work pretty much out of the box. Some get a little confused about how such a thing could possibly exist, but I can’t really fault them for that :)
The problem about assumptions is that we can't live with them, but we can't also live without them.
Many so-called "cross platform" projects have had big surprises when it actually came time them to be ported to other platforms.
It's extremely rare for a project which has never been compiled and launched on another platform to actually require 0 porting effort for that platform once actually required to run there.
Yes, for all but the simplest or most abstracted projects sticking steadfastly to standardized features this is fairly hard to do. But the closer you stay stick to that, the more platforms your projects has been through, the more foundational (and less dependency-heavy) your project is, the more likely it will port with few or any changes. My preferred shell and text editor, for example, required zero changes; as did many core tools such as ncurses or make or autoconf. And on top of those it was easy to get things like perl or ninja up with perhaps a small tweak to their configure script or something.
The lowest common denominator leads to working with Stone Age tools. I'm not surprised that not everyone goes that route.
And regarding your porting, Perl, sure, was easy to port. What about CPAN? Want to bet how many Perl libraries will keel over? Same thing for Ruby/gems, Python/pip, etc.
Don't get me wrong, your work is nice, but the people that build on top of your work outnumber you by 2-3-5 orders of magnitude and not all of their porting efforts will be trivial.
This was the extent of the changes necessary to get Meson working on the system-provided Python: https://github.com/mesonbuild/meson/commit/85686e21d78a587de.... Surely that is not a "Stone Age tool"? The people doing the work right now to get foundational stuff working are doing that precisely to aid the porting efforts of the many, many developers that will depend on those things working in a few months when they have to port their own codebases.
