The XDG environment variables only apply to systems where the XDG spec is defined to be in place. You need one extra flag for defining that to be true. Given th

The XDG environment variables only apply to systems where the XDG spec is defined to be in place. You need one extra flag for defining that to be true. Given that macOS isn't a place where XDG is applicable, suddenly making it applicable would break every place that assumes that it's not applicable (e.g. I no longer have configuration for some utility that uses the pre-change value of the AppSupport folders.