One of the main reasons why I avoid softwares such as Kopia or Borg or Restic or whatever is in fashion:
they go unmantained
they are not simple: so many of my frienda struggled restoring backups because you are not dealing with files anymore, but encrypted or compressed blobs
rsync has an easy mental model and has extremely good defaults
Going unmaintained is a non issue, since you can still restore from your backup. It is not like a subscription or proprietary software which is no longer usable when you stop to pay for it or the company owning goes down.
The design of restic is quite simple and easy to understand. The original dev gave multiple talks about it, quite interesting.
Imho the additional features of dedup, encryption and versioning outweigh the points you mentioned by far.