Orphaned works are most certainly not a fiction. As someone who regularly works with libraries, archives, & museums, I can say with some certainty that orphan works are huge problems for such entities, and copyright law as it's currently instantiated ensures that these works may disappear forever. Orphaned works are the majority of works in existence.
See the Copyright Office comments (and the US Copyright Office favors strong copyright laws)
See the Association of Research Libraries comments to the Copyright Office
See the Society of American Archivists Best Practices
See some of Peter Hirtle's comments.
Orphaned works is a huge issue, and will become more of an issue as we attempt to work with and preserve digital works.