It has one: immutable paths:
... "Since there’s a controlled number of points that can make paths, you can set rules for them (e.g. no fewer than two elements, no paths-in-paths). And since there are no direct modifiers, they can’t be changed to disobey this rule."
... "I’ve wondered if a/(b): c is superior to the point that the path creation rules prohibit embedded get-words. If you couldn’t put any GET-SET-LIT inside path elements, it could stop ambiguities."
... "Furthermore, some types (like FILE! or URL!) have slashes in them. Should inserting them into paths be an error, or at least use those slashes to point out where path segments are and split along them?"