For hardware failure, replication is the bees knees and indeed means you'll lose less (no? depending on your replication settings) data.
But, backups will help if you replicated _bad data_, or more accurately _data changes_.
You can restore from backup if you accidentally ran `DELETE FROM foo;`, where replication will not help!
(Insert cryptolocker type viruses, bugs, human query mistakes, etc).
I imagine in that scenario the engineering team can develop inter-dimensional travel, then travel to a universe in which that command was never executed. They bring the data back and restore the database.