Regular reminder: RAID (and ZFS) don't replace backups. It's an availability solution to reduce downtime in event of disk failure. Many things can go wrong with your files and filesystem besides disk failure, eg user error, userspace software/script bugs, driver or FS or hardware bugs, ransomware, etc)
The article mentions backups near the end saying eg "most of the data is not important" and the "most important" data is backed up. Feeling lucky I guess.
ZFS can help you with backups and data integrity beyond what RAID provides, though. For example, I back up to another machine using zfs's snapshot sending feature. Fast and convenient. I scrub my machine and the backup machine every week, so if any data has become damaged beyond repair on my machine, I know pretty quickly. Same with the backup machine. And because of the regular integrity checking on my machine, it's very unlikely that I accidentally back up damaged data. And finally, frequent snapshots are a great way to recover from software and some user errors.
Of course, there are still dangers, but ZFS without backup is a big improvement over RAID, and ZFS with backups is a big improvement over most backup strategies.
The article mentions backups near the end saying eg "most of the data is not important" and the "most important" data is backed up. Feeling lucky I guess.