I posit that the OS Checklist is fairly long and that no of the other systems you mention have the complete OS package. They do. E.g. SmartOS is a UNIX. It'd

I posit that the OS Checklist is fairly long and that no of the other systems you mention have the complete OS package. They do. E.g. SmartOS is a UNIX. It'd be pretty odd if it didn't have an init system. Or storage. Or cron. Or POSIX. Or whatever else you'd like to add to the list that UNIX systems usually have...