B2 can't do simple things like move or copy,[1] so in my opinion it's really bad for those kinds of applications. For example, if you move a 5GB video file, you shouldn't have to delete+re-upload the entire thing just to change the path.
Using a file storage service like B2 or S3 as a file system is a bad idea anyway. You won’t be able to use features such as deduplication and incremental backup.
It’s better to use an external tool such as Restic or Duplicacy. So moving 5GB file is just a matter of changing a few KB index file.
In the case of my home video and pictures, I have terabytes of data that is largely unique+incompressible so the "dedupe" step on every backup program I've used so far takes a ridiculously long time and yields approximately zero space savings.
Incremental backup I also don't care about because `s3 sync` already only syncs what changed, and I don't care about restoring to previous versions because I want it to be an append-only store, which S3 versioning gives me.
I also need it to be simple for my family to recover data from in case I die suddenly, so I don't want them to have to decode some binary format to get at our pictures and video.
[1]: https://github.com/Backblaze/B2_Command_Line_Tool/issues/525