Sorry the geometry of modern datacenters doesn't mean 1000 4TB disks ='s 4 PB Raw. You are thinking on a home datacenter scale.
Deduplication works on scale. The bigger the better.
Given enough data and enough storage, you could have almost infinite storage with finite physical storage.
The only issue is power consumption, for feeding all these disks and all those AC's cooling them (reason why free cooling is such a buzz word now).
However bandwidth is NOT finite and for them it's one of the primary costs for them. That's why all of them (google, aws, etc) have their own multi fibre backbones and networking plexes.
So, if you abuse their network (fuse mount of rclone) that WILL cost them money effectively.
If you hog their cpu's on their ACD frontends with pull's and get's like mad as the fuse mounts do that WILL cost them money.
That (besides the very SERIOUS security issue) is the problem.