You should not bank on 1 backup, but at least 2 (1 of which is offsite). So you have original, on-site backup, off-site backup. In case of big trouble e.g. fire/burglary/disaster, you still got your off-site backup. Your on-site backup could be a NAS or USB stick, and your off-site backup could be on Backblaze. You only use the off-site backup when your on-site backup fails. At that point, you need to shell out money, because it costs money to download the data (costs per GB). Dedup saves you space. With incremental backups, lots of it. Saving space saves you money. Both on retrieval and on storage. All that Time Machine does for you is a really nice UI allowing you to go back to snapshots. Git allows that, too. ZFS and Btrfs allow that, too. I'm not aware of a UI as good as Time Machine though; that is the problem. But for an off-site backup, maybe you don't require that.
I am afraid you missed the point I was stressing about TM. It’s not the UI for me but the UX. The ability to restore a blank HDD to a macOS + state of all applications (including cookies and cache that’ll allow you to “go back in time”).
Agreed on other points about offline storage and offsite backups. I just think TM has its place and backblaze/syncthing has its own use case. My argument is you can’t replace one with another.
