NeXTSTEP was 4.3BSD plus Mach, using Display Postscript as its windowing system and TIFF as its image format, supporting transparency for icons. macOS is FreeBSD plus Mach, using Display PDF as its windowing format and PNG as its image format, supporting transparency for icons. Basically NeXTSTEP but every component upgraded to its then-modern equivalent. (Except Objective C, they kept that.)
> Bell Labs did the same with Unix, but Unix was still not open source. This is why we run GNU/Linux today, not Unix™.
I know pretty well how NeXTSTEP used to be, my graduation project was to port a visualization framework from NeXTSTEP/Objective-C to Windows/C++.
The fact that UNIX™ later went on to become a compatibility specification, not a specific implementation, is irrelevant to the analogy.
Without that leak we would not have the ecosystem evolving around Llama.