I'm not sure it's a question of FOSS OS vs non-FOSS OS. Working with MacOS has always felt similar to working with other non-Linuxes -- it's different. When OSX first came along with Rhapsody, while it was a form of UNIX it was definitely painful - stuff rarely built out of box, and there was lots of breakage. It surprises me when people talk about how wonderful OSX used to be that they forget how absolutely painful it was for the first few years of its existence. There was a brief period between 2005 and 2013 when stuff worked reliably (the "golden age" you refer to) - and it wasn't a matter of OSX becoming more open. It was just popular, so OSX was a first class citizen in most configure scripts and the OS didn't really put up any barriers to using it like a Linux with respect to the Linux security/permissions model.
The added restrictions of recent times (e.g. SIP, the move to a non-GNU build toolchain, hard read-only restrictions on the OS region of the filesystem, etc) aren't so much a FOSS issue as them just adopting conventions that aren't present on the Linuxes. The breakage of packages and porting efforts feel very similar to when we used to have to worry about how a package would work on HP-UX, Irix, Solaris, and the various systems that were all similar but not quite identical. That was never a function of FOSS or not - it was just a function of not being all the same.
I find it very frustrating that people try to treat OSX as a Linux - it's not, and it never will be. If you want to support macOS, then support macOS - don't try to bash Linux-isms onto it since they will always feel like a hack since it isn't and never will be a Linux. If that's important to you, there's an easy solution - use Linux. I do that - I have my MacBook that I use as a Mac, and for the stuff that's simply too awkward to use natively there, I just ssh to my Linux workstation and carry on.
The added restrictions of recent times (e.g. SIP, the move to a non-GNU build toolchain, hard read-only restrictions on the OS region of the filesystem, etc) aren't so much a FOSS issue as them just adopting conventions that aren't present on the Linuxes. The breakage of packages and porting efforts feel very similar to when we used to have to worry about how a package would work on HP-UX, Irix, Solaris, and the various systems that were all similar but not quite identical. That was never a function of FOSS or not - it was just a function of not being all the same.
I find it very frustrating that people try to treat OSX as a Linux - it's not, and it never will be. If you want to support macOS, then support macOS - don't try to bash Linux-isms onto it since they will always feel like a hack since it isn't and never will be a Linux. If that's important to you, there's an easy solution - use Linux. I do that - I have my MacBook that I use as a Mac, and for the stuff that's simply too awkward to use natively there, I just ssh to my Linux workstation and carry on.