I've seen AFD used by one "conversational" list to produce an editted
digest of the discussion by the owner.

As Peter.R said, it was useful to package related files such as software.
 When one of the elements (files) of the package got updated, it (or the
notification) was distributed.  If the developer added a file, it too was
distributed.  Likewise, if the developer DELETEd an element, notification
was sent.

In the good 'ol days of Bitnet, I used to subscribe to FILELISTs
themselves (when they did NOT contain active discussion, but were
repositories of info e.g., NETINFO at BITNIC, or CONTROL at VM/CMS
sites).  After all, the FILELIST was (is) a file.

Much of all this was used before the WEB and HTTP became popular.  Don't
know if that is related, though.

/Pete