Why does the integrity of the backup rely on files stored on the computer being backed up? This seems so stupid that I'm sure I'm missing a clue.
Reading the explanation in the reddit thread, that's not the impression I got at all.
1. If your computer exploded, your backup integrity would not be compromised
2. If gremlins in your computer did mess with the file, your backups could be compromised. That sounds bad, until you realize that gremlins in your computer could also compromise the executable to do other things that could compromise the backup, (eg. telling the server to delete existing backup data because the retention period has passed or whatever, or simply uploading bad data and waiting for the retention period of 30 days to pass). Moral of the story: if the computer doing the backup can't be trusted to operate correctly, all bets are off.
But I can't do that without knowing which files are missing.