Nostr added benefits over normal email lists are small, but meaningful:

- cryptographic signatures for messages

- multiple client compatibility

- people who are not allowed in the mailing list are still able to comment about the topics posted to the mailing list, they just have to push their comments to other relays, parallel discussions can arise

- instead of a single central relay, you can have a different one for each moderator, and people can pick the moderators they trust more (they don't have to run servers, there could just be a relay provider that runs a single server but isolates one relay from the other by URL and providers a nice interface for the moderators to use)