Sorta. At the end of the day, yes, the disks are being managed by your CPU and not a dedicated raid controller... but it's a completely different ballgame than something like mdadm.

Not "sorta", it's software raid and thus, like software raid, it's portable to any system that'll run the software and JBOD the drives.

Most would argue RAIDZ is better, but many of these reasons are functionality based over and about just redundancy, i.e. Copy on Write, et all.

Friends don't let friends create RaidZ pools.

Bite the bullet of the cost of N*2 mirrors.

I say sorta because in most circles when one is speaking of 'software RAID' they are referring to a very specific configuration and are explicitly not referring to ZFS.

ZFS doesn’t support hardware RAID controllers?

It supports it, but ZFS itself is operating on the host CPU, not the RAID controller. Additionally, ZFS prefers that the RAID controller is disabled/defeated and operating in JBOD mode where disks are passed-thru to the OS without any caching.

Not just caching. The problem is that non-JBOD HBAs also swallow error codes and mask retries, meaning ZFS is potentially unaware of some read errors and is not in control of the latency as the controller firmware has its own timeouts and retry counters. Moreover, most will not pass through SMART or else fake it.