I have written about this some time ago if you’re interested: https://www.franzoni.eu/ransomware-resistant-backups/
So it's not just ease of use. It's actual _functionality_ to me - getting from raw object storage to a fully working, attack-resistant backup strategy, is not trivial; hence, comparing tarsnap (or rsync.net, or borgbase, or whatever) to B2 or S3 makes little to no sense.
You _could_ compare it to crashplan or backblaze personal backup if you like, but IIRC those don't work for *nix systems, only for Win and Mac.
Those restrictions are enforced by the service.
There's also a service like rsync.net where you can just rsync to the destination and they do the versioning and so on for less than 10th of the cost of tarsnap.