I found the URL addressing scheme of Redox to be fascinating, if perhaps slightly less user-friendly compared to files and file paths.
Having a scheme:// makes sense for URLs because you don't otherwise have any contextual information indicating how to access a resource. But this isn't the case for something like a virtual filesystem, where the total set of filesystems mounted under it - and their types - are all known to the system. There's no need for disk://foo when you can just have /dev/disk/foo.
If that's not the case, I have found the scheme to be helpful to indicate what's going on.
What the use of schemes does is make things needlessly inflexible, and embeds a dependency on the name of a filesystem provider inside consumers of that filesystem. It's akin to a Unix where filesystems can only be mounted in top-level directories /mnt, but not /mnt/foo, etc.; I don't see the appeal.
Why?
mount -t type device destination_dir
Unless I am missing something in your use case.
Not so. See file: :-)