well, as im as new as this protocol, im looking at the possibilities. i think that a relay that is completely open allows for a client that can at least sort/filter by nip/kind (and if i have my way, geohash).  i think that key here is that a client with a simple enough interface could sort by more than the conventions offered within the protocol, but by content, author, and other metadata.  i dont see why this couldnt/wouldnt be implemented in damus or primal, but again im new here and still havent fully assessed the landscape.