Linux still lacks the multitenant security guarantees of Solaris Zones but this isn't so bad. Hard multitenancy is a problem that only concerns a fairly small subset of people and even then, there are solutions. You can do hard multitenancy with Linux containers (namespaces/cgroups to be pedantic) if you start restricting the system call table. There is also Firecracker[1] which obviously isn't as efficient as Zones (because it uses VMs), but is proven in production and does provide additional security guarantees.
The technical advantages of Illumos are outweighed (or rivaled) at this point, in my opinion. When I show people things on my laptop, I always end up talking about the desktop cube in KDE or my neovim/tmux/zsh setup. Due to ZFS snapshots and the power of zfs send/recv, I expect this system installation to last for years to come. No more reinstalls, we're good, this operating system thing is covered.
1: https://github.com/firecracker-microvm/firecracker-container...