Earlier quoted context omitted.
Yeah, same here. Like, what's the point of an "operating system UI" in a Linux desktop environment? But then, I also don't get the point of doing that in some game engine called Unity. I mean, is that a viable way to do a desktop?
The point of doing an operating system UI in a game engine is so that you can use that operating system UI within games written in that engine! There's several examples - Simulacra, Emily was Away, Hypnospace Outlaw - that use the interface of an (imaginary) computer as their primary framing device. Or it could be useful in an immersive-sim type game where there happen to be computers you can interact with; you could…
So yeah, I get it. Of course there'd be computers in games.
But once you have an OS in a game, why not just run a VM? Or would that use too many resources?