First of all, that's not a backup, that's a snapshot, and NO, that's not "good enough", tell your grandma that all her digitised pictures are gone because her hard drive exploded, or that one most important jpeg is now unwatchable because of bitrot.

Just because someone is a private user doesn't mean that the data is less important, often it's quite the opposite, for example a family album vs your cloned git repository.

... VSS is used to create backups. Re-read parent.

Not good enough, you can make 10000 backups of bitrotten data, if you don't have check-sums on your block (zfs) or files (restic) nothing can help you. That's the same integrity as to copy stuff on your thump-drive.

The same applies to those filesystems on Linux which don't check for bit-rottenness, which will be the majority of installs.

Your average grandma would use ext4 when using Linux. Android phones don't do that as well and I don't know about iOS, but apparently APFS only does metadata checksumming.

>> if you don't have check-sums on your block (zfs) or files (restic)

....