Mac OS X got it's first (server) release in 1999. And even that was a reboot of Nextstep which was originally released in 1989.
Of course, the whole point of Chrome OS is (apparently) to not have a traditional GUI and apps, just a browser, which is most of the stuff Apple had to add onto BSD.
I meant my comment in the context of the message I replied to. In that in 2002 they first tried to push a new OS to the desktop market as it was then. From what I heard about it, nextstep was not anymore advanced compared to the rest of the market than Linux/Ubuntu/Gnome is now to it's market.
I don't believe any company could afford to start back right down to the kernel and low level libraries for a new desktop OS, even it was just going to run a web browser. I would say that any competitor to Apple and Microsoft would have to use a Linux kernel, CUPS etc. as a base - just as OS X used NextStep/BSD as base.
The problem, of course, is the effort. Software is hard.