On nostr, nobody takes responsibility for what others talk to them and only mildly endorse those they follow. Relays are just the broadcast substitute because we have no always-on-and-not-censoring-relay we all can just agree on.

If we give credit to your concept of "Alice picked this inbox. Alice endorsed messages *to her* on this relay" then maybe we should allow for Alice to actually see whatever she gets there but also consider "Alice follows Bob but not Carol" so maybe we should show potential spam videos from Bob bot not from Carol client side? And for the more concerned, only show own follows' content?

I am absolutely convinced that we don't need new masters. Don't make relay operators the arbiters of what is spam and what not. Let them mark stuff as spam as a service or what not but ultimately the clients have to get resilience independent of chosen relays.