I would argue in conjunction with zfs snapshots (can be every minute), it's safe and the caveat no longer applies.
I'm really not super familiar with Syncthing, but it sounds like it's niche is availability as opposed to durability.
Anyone taking backups seriously already knows the 3-2-1 rule anyway.
This is the curse of sharp tools. Don't run unix if you don't want rm to rm.
I still also have backups, and zfs snapshots on a different independent machine.