Have you ever tried modifying the filesystem a couple levels under /?

Last I used a Mac I remember trying to create a new directory in / and writing to /bin (or something like that). I was appalled that Mac doesn't let you do anything other than read-only operations for select paths a few levels under root, and as I remember, there way no way to disable this asinine behavior.

I say this as someone who has used Unix, MacOS and Linux for most of his long life: not being able to write to /bin and other system directories is a feature and I really don’t understand how anybody in 2023 could see it otherwise.

Freedom does not just imply the ability to do the things you want, but also the ability to avoid the things you don’t.

Why 2023 writing to /bin was always a bad idea in 1994 when I first used Unix and would have been so even earlier.

You can just mount it readonly.

Yes which as I have said done since the early 1990s

lol what?

What's the point of this exercise? Is this some kind of power play against the... operating system?!

Did this prevent you from achieving anything?

In any case, I'm fairly confident if you disable SIP and do a couple extra steps, you can get write access to those.

OTOH it is the same for an "immutable" linux distro.

That specific example doesn't seem to be an issue anymore. The Nix Installer creates /nix/store on macOS 13.5 just fine without disabling SIP. You do need admin rights of course.