When it comes to MBA enclosure it's likely the infill or separation problems with long thin walls that led them to abandon injection molding. Even then it's not done on a mill in one take. Things like speaker grilles are probably something like EDM or etching rather than 8000 operations with 0.2mm drill bit.
And as far as parlor ticks go this is not particularly impressive, compared to old ones like turning cube inside a cube on a lathe.
Tools like UNISURF would probably not be able to handle the extreme level of detail on most of that model. The very long tool lengths you see in the video are much more complex than they look and require effort both from software and hardware to prevent chatter and breakage on titanium. The clearances in the video are also extremely tight in places, and while you could have guess-and-checked that in the 70s, it’s a very different workflow than the simulators that are basically standard use today.
CNC machining is a multi-billion dollar industry populated by smart people. While the fundamental technology of “spinning cutter driven by computer controlled motors” hasn’t changed in 50 years, the R&D departments aren’t asleep at the wheel.
