I can't think of many (any?) reasons to run this. The Darwin part of macOS is the least interesting and least capable part of the operating system.
Edit: I used to spend a lot of time hacking on Darwin code until I realized that Apple wasn’t really into open sourcing it. It was just some check mark to check off on.
I went down this rabbit hole for a while at University. I might come back to it one day.
These were available in Apple's open-source Libc until (afaict) Libc versions 9xx.x.x, corresponding to Mac OS X 10.9.x: https://opensource.apple.com/source/Libc/Libc-997.90.3/inclu...
They were also available in the Mac OS X / macOS SDK package from as far back as I could find (10.1.x) through macOS 10.11.
macOS 10.12 introduced the new equivalent `sysdir` and deprecated `NSSystemDirectories`. These were only ever available as part of the SDK, not in Libc.
Is it purely from some license restriction of some software they use?
The next best reason is normally something like "open source code tends to proliferate", like openSSH, Linux, git, etc. But Darwin does not seem to be thriving in this way - from the page, it seems to be a small hobbiest community, and it's not like Apple needs to depend upon the community for their core OS to thrive.
I'm definitely happy Apple releases Darwin as open source, so don't interpret this as me criticizing that. I'm just trying to understand their motive.
How behind is Apple OS from the latest FreeBSD releases?