The more general principle is that single source of truth is not ideal for data storage where you're worried about corruption. There's a backup MBR on your hard

The more general principle is that single source of truth is not ideal for data storage where you're worried about corruption. There's a backup MBR on your hard disk at the end, your ext4 filesystem has many backups of your superblock. When it comes to user data the natural programmer instinct for "is exactly what I expect or fail" which is typically good design, falls to pragmatism where try your hardest to not lose data, partial results are better then nothing, is desired.