The core property of #nostr is that it is a permissionless protocol; any relay may join. (Analogous to Bitcoin's decentralization). In this light, banning relays would mean fundamental failure.

I don't think privacy is a central element, our data is out in the open, even moreso than when posting on mainstream platforms because there it is behind closed doors (they have an incentive to protect it in order to better & exclusively monetize it). However, the fact that anyone can create an nsec/npub without any kyc does benefit privacy.

Success (IMO) means that a significant portion of "public square" conversations are held on nostr