dwww need not be limited to localhost access, meaning that a single Debian system can serve docs to others (LAN, intranet, public Internet, ...).

Of course, all of the documentation that's exposed via dwww is accessible on that host's filesystem. But dwww also provides a few additional affordances: Web-formatted output, a directory of installed documentation (organised by source / type), and (if you have swish++ installed), full-text search.