I don't know the details about Haiku, but at the end of its life, BeOS had some kind of multiuser support, in that the OS was aware of UNIX-like permissions in

I don't know the details about Haiku, but at the end of its life, BeOS had some kind of multiuser support, in that the OS was aware of UNIX-like permissions in the filesystem (and for processes I think). But there was no GUI for logging in, so you were always root. It was meant for single-user workstations. Not having multiple users was not really a problem, except that it made (makes) some people look down their noses. In this day and age, the main security issue on my workstation is that I all applications - including the browser that downloads a bunch of untrusted code and runs it willy-nilly - run as the same user that owns all my important files. I'm a lot more concerned about what's in my home directory than anything under /usr! So if and when Haiku adds security measures to isolate applications from each other, I would prefer they looked at some kind of sandboxing to isolate every app from each other, rather than just copying the basic UNIX model, which does basically nothing for the problems people actually have. (OK, if you need to share a computer which another person you can't have separate settings and browser histories etc., but.. I don't know if that's really such a big deal that it needs to be tackled before the other one)