Back to fundamentals again for a moment.
Yes point in time copies are backups but they don't protect you from a system failure.
Getting a copy of the data off the system protects you from a system failure.
We've had occurrences of this show up in public already this year where an upgrade to a storage system resulted in the loss of millions of user photos. There is no number of snapshots that was going to bring that data back. The fact the data had been backed up off of the system is what allowed that data to be recovered and normal operation resumed.
I'm a big believer in rolling the last point in time copy of the day off the system and over to different media during the nightly backup window. Take some copies during the day, once every 8 hours isn't bad assuming it meets your RPO..
Recovery Point Objective (RPO)
[Data Recovery] The maximum acceptable time period prior to a failure or disaster during which changes to data may be lost as a consequence of recovery.
Data changes preceding the failure or disaster by at least this time period are preserved by recovery. Zero is a valid value and is equivalent to a "zero data loss" requirement.
..and then have a backup application roll the final point in time copy of the day over to disk, virtual tape, physical tape or whatever backup media you're using so long as it isn't located on the same system.
While point in time copies are backups the question you have is if you're only doing half the job when it comes to ensuring data recovery.
