I worked on an OS like that once. The problem is with "all the other stuff" that you need to support that's outside the core mission of your OS. You wind up b

I worked on an OS like that once. The problem is with "all the other stuff" that you need to support that's outside the core mission of your OS. You wind up bogged down on each additional feature that you need to implement from scratch (or port from another OS with a compatible license). With FreeBSD, all this comes for free. We chose to use FreeBSD, and have contributed our code back to the FreeBSD upstream to make the world a better place for everyone.