I don't think that nostr would work well with too many relays. The fact that nostr uses public key cryptography makes it inherently better than alternatives such as Mastodon, where you're screwed if the instance just bans you. With nostr you can take your identity to any of the relays available.

Therefore it just takes one of the relays to accept you. In the worst case where literally every relay has banned you, you can self-host a relay.