> this should be sufficient to represent the file.

Except it's not, because the oid can be a short hash (https://github.com/gritzko/beagle/blob/a7e172/VERBS.md) and that means you're at risk of colliding with every other top-level entry in the repository, so you're restricting the naming of those toplevel entries, for no reason.

So namespacing git object lookups is perfectly sensible, and doing so with the type you're looking for (rather than e.g. `git` to indicate traversal of the git db) probably simplifies routing, and to the extent that it is any use makes the destination clearer for people reading the link.