On Mastodon, everyone's account is tied to a Mastodon server.

On Nostr you control your account. Only you know your private key, so nobody can ban your account. Sure, Nostr relays can ban you and individuals can block you, but you can't be banned completely.

Host your own relay, put it as an outbox relay in your Nostr profile and you're in-bannable. Anyone that follows you can find you and repost you.

It's much easier and fool proof than Mastodon.