Compared to a DHT? especially one that you don't have to implement because it is already implemented plenty and you only need one function call to find exactly where the endpoint is because the user authoritatively said so?

Outbox model not at least an order of magnitude harder to deal with? Forget about the happy path when both you and your target use the same relay set... let's talk about what happens when you don't and you have to find the relays they published their profile on.