I wasn't referring to syncs at all, but actual point in time backups, so I agree.
There are syncs that can also be configured to not to delete. It's how syncs can do version control.
If you use an off the shell backup or NAS like a Synology or QNAP it will take care of all of that for you. You can plug in external drives to it for copies, an then also have the NAS ship off backup copies to multiple places.
Since the cloud is someone else's computer, it's good to have your own copy of it too on your own hardware.
Hope that helps.
Data is valuable, worth learning to protect :).