Just a year ago B2 couldn't do server-side file copying.[1] If you wanted to rename or move a file you had to re-upload the whole thing (not great for large multi-gigabyte files)! That ruled them out of consideration for storing my personal backups. Glad to see they've since fixed that, and with this update are clearly continuing to improve ergonomics. I'll have to give B2 a fresh look. [1]: https://github.com/Backbl…
For backups, mapping one file to one object rarely works well. Tools that use this strategy come with a long list of scenarios requiring expensive operations. For instance renaming a directory or changing a few bytes in a large file. On the other hand tools that don't view the object storage as a file system have way less gotchas. In my experience B2 + restic works really well.
Same for archiving. At my former workplace we however figured that out only after the horse left the barn.