You mean except for being able to:
- use encryption
- ransomware protection
- zero trust
- verifying backups so you aren't screwed when you need to restore it but it silently corrupted
- saving tons of space because of deduplicaton (storing 12 monthly + 4 weekly + 7 daily + 24 hourly backups with PBS will probably consume less space than 2 or 3 daily backups with VZDump)
- incremental backups possible (so less wasted bandwidth and backups will only take a fraction of the time)
- live restore (so you can run that VM even while it is still restoring)
- syncing backups between multiple PBSs (great for your offsite requirement of the 3-2-1 rule)
- single file restores so you can get a file of a VM without needing to restore the whole VM
...