Hurd translators don't have to export virtual file systems. They go beyond that into being generic object servers and are also used to implement things like a regular Unix TCP/IP stack (pfinet), Unix process semantics like pids, sids, wait()ing, parent-child relationships, groups (proc), authentication (auth) and so on.

They're more similar to Spring's name server mechanism, being general object brokers as opposed to file object brokers in particular, as is with 9P/Styx.