I've seen this happen to a friend. Back in the noughties they built a home NAS similar to the one in the article, using fewer (smaller) drives. It was in RAID5 configuration. It lasted until one drive died and a second followed it during the rebuild. Granted, it wasn't using ZFS, there was no regular scrubbing, 00s drive failure rates were probably different, and they didn't power it down when not using it. The point is the correlated failure, not the precise cause.
Usual disclaimers, n=1, rando on the internet, etc.
Usual disclaimers, n=1, rando on the internet, etc.