I hate this take, and it seems to contradict itself.

What actually counts A copy counts when it survives the loss of the thing it was copied from. That one sentence settles most arguments about what is and isn't a backup.

So doesn't raid count then? If a drive fails and the second drive survives the loss, it is a backup...

Just because the copy is synchronous doesn't mean it isn't a backup, it just means it protects from a different type of failure.

• RAID: protects against a drive failure
• Snapshot: protects against user failure (rm *)
• Replication: protects against admin failure (zpool destroy)
• Offsite tape/async backup: protects against replication corruption, and total site failure

These are all backups, just with different recovery point objectives/recovery time objectives, and all just as important.