Yes, relays should fight spam better. However, WOT is a failure and ruins the experience. Every other decentralized alternative don't have these problems. Only Nostr because of their bad design decisions. They never cared about the relay. Wot is a poorly designed bandaid to cover up bad relay design decisions. Nostr can't even fight CSAM  

 Your right it does hurt discovery. I just like when I can control it. I limited everything to like 2 relays, then stopped seeing things in certain clients, added a couple back. Choosing relays still confuses me I suppose.