> Pinning this squarely on user error.

It isn't user error if it was working perfectly fine until the provider made a silent change.

Unless the user error you are referring to is not managing their own backups, like I do. Though this isn't free from trouble, I once had silent failures backing up a small section of my stuff for a while because of an ownership/perms snafu and my script not sending the reports to stderr to anywhere I'd generally see them. Luckily an automated test (every now & then it scans for differences in the whole backup and current data) because it could see the source and noticed a copy wasn't in the latest snapshot on the far-away copy. Reliable backups is a harder problem then most imagine.