"Presumptuous" meaning it presumes what a user will want to do with a computer. In this case, the computer comes with no display, no keyboard, no mouse, no trackpad, etc.
I'm not following. Are you saying that one can use an Apple router with an alternate free operating system and it still functions as a router ? I'm not aware of any such project. At least openwrt does not support the Apple router. As for what users would want to do, that is a moot point since there are common expectations for devices based on the specs and form factors. So, why would you buy a $2k laptop to use it as an inefficient, buggy, and underpowered headless linux server (assuming you get networking working)?
The "alternative OS" is the OS that Apple used for its AirPort Extreme router, and which it borrows heavily from for the MacOs userland. Apple writes some software itself, but it also takes a significant amount of source code straight from "alternative OS" projects. To be clear, the OS projects I am referring to are not Linux nor is the computer that is the subject of this thread a "$2K laptop".
Do you mean to imply that those things are known not to work?
There have been many Apple devices where all those mentioned things (if present) work under a non-Apple OS. So as usual the truth is somewhere in the middle. From my Linux experience there are a lot of well working MBP models from this time span. And Minis.
It's not. Anyone who has followed the last 10 years of Apple devices knows what works and what doesn't.