This would seem to make it the best backup system, you can merge your incremental backups over time, so never have to reset, without requiring any backup storage software on the remote computer, and it's never decrypted
I totally agree. I actually just built some scripts to do this using rclone, but they could easily be modified to work with a remote ZFS which is actually way more ideal. It is encrypted in-flight, and at rest on the remote, and merging block-level increments never require decryption. My key never has to leave my local machine.
Tools like Duplicati and Cryptomator also allow this. I'm using Jottacloud, 7,50 EUR for 5 TB (actually 'unlimited' but the speed gets slower after 5 TB). Rclone also has support for Jottacloud. Nice thing about Jottacloud is its hosted on Norway. They got privacy laws there. I know if you encrypt in-flight without having your private key remotely this is far less important, but still. Arguably, these products are therefore competitors.