[mort96]

It's not really a "backup" if it's just on the same server/data center though. Moving data from one drive to another in the same machine, or from one machine to another in the same building, provides fault tolerance should the main drive/machine die, that's about it.

That's true whether the computer(s) is your own or someone else's.

[z3t4]

It's all about threat model. And yes "our cloud provider accidentally deletes both our data and our backups" should be in the list.