gossip is needed for both bitcoin mempool and for lightning for different reasons

yes, they reduce the chances of partitioning

that's the first reason it helps resist censorship

second, gossip is needed for a source routed protocol like lightning because clients have to decide where to forward every hop of the payment, they can't trust the nodes on the path to decide for them, and actually, the cryptographic reason is they define the path because it's cryptographically secure

that's why we have AMP, because if any point a client chooses, is offline, or has a banked up network buffer, our payment fails!

that's why lightning has a problem and that's why nostr now has a problem because this is not appropriate for nostr at all