Except NeXT did it in 1989, not 1990s. And OS X is based on FreeBSD 3.5... 4.5 *just* came out. Not sure which BSD you're referring to, but OpenBSD didn't even exist then, and NetBSD isn't close to version 4.4 yet...
Anyway, point stands. Steve did it before them with NeXT anyway, so they...