I mean, not that I really figured it out. That's just kind of how Ditto works out of the box. Ditto comes with yourdoimain.com/relay is your instances relay. If you don't add any other Relays to your instance of Ditto, it only reads and writes from itself. 

For some reason I felt the need to add other relays to the instance of Ditto when I first set it up and that it ingested a whole bunch of random crap into the global timeline. Not really ideal for a themed relay.