To be absolutely fair, the first adequate namespaces implementation came out in kernel version 3.8, so that puts us in 2013, when talking capabilities to run %process% in a "container". Admittedly, a few years later than illumos. But then again, illumos was just playing catch-up with *BSD back then, as jails were available since 2000 ;)
By the way, what is your primary motivation for using illumos? genuinely curious.
