I'm sorry but you're just plain wrong. According to the canonical BeOS Bible there is a POSIX layer and some rudimentary kernel support for multiuser permission

I'm sorry but you're just plain wrong. According to the canonical BeOS Bible there is a POSIX layer and some rudimentary kernel support for multiuser permissions, these were never fully implemented nor exposed. (Developed BeOS applications in the late 1990s.) https://www.amazon.com/BeOS-Bible-Scot-Hacker/dp/0201353776 https://www.amazon.com/BeOS-Bible-Scot-Hacker/dp/0201353776