If Apple would open source some of its OS apps, this would probably be a non-issue, I could see people putting in bugfix PRs the second Apple chooses to open source their core apps.
I don't see them doing this any time soon sadly, but it would make macOS much more stable, and probably secure.
The more I have thought about my views on Open Source vs Commercial software, I strongly feel that infrastructure code (an OS) should be more open source, I dont see Microsoft or Apple open sourcing any time soon, but it would make a world of a difference, imagine a world where Windows XP had been open sourced, and the community took it fully over and maintained its security, you'd have a drastically better version of Windows without all the fluff, or heck even Windows 7, which some argue was the last good version of Windows as well.
I wish ReactOS was drastically more usable.