Nostr relays can censor however much they want. And users can just add other relays and route around it. That's fundamentally different from most other protocols, where user identity and posts are tied to a single server, and there is no means to just broadcast to another one.

On Lemmy for example you can't even find a post another server, since post ids are tied to a server. So despite post actually being cached on multiple servers, it provides absolutely nothing that helps with censorship or crash tolleranze.