> Other things: since no companies sponsoring its development had any interest in raid 5/6, which is mostly a home enthusiast thing.

I've used RAID-Z1/2/3 at a couple of jobs: yes IOps is suck-y, but if it's for backups of other systems, or the central logging server, or network monitoring (Suricata, Snort), sometimes your priority is cheap/bulk.

I'm currently in the HPC space, and Lustre is a thing here, and it has tiered storage via policies: you can (e.g.) put your recent/hot data on NVMe, but older/colder bits on spinning rust on ZFS.