Relays should be as discriminatory as they please, totally! I hope to see many relays with all kinds of trade-offs. There's not point in telling relays what to do but I want a client that can produce great results when reading from all relays and not just one unless that one is my trusted relay that does the heavy lifting for me - like event de-duplication.
But the default is that I don't trust your relay and I would hate to give you the power to even delay the delivery of events to me.
So maybe the confusion is that these are all "relays" and I would hate people to only read from the primal relay while you are talking about proxy/caching relays. I think you say "read" relay. Inbox/outbox, ... it's all a bit confusing.
