Another thing that #nostr does is that it decouples the concept of a ‘certificate’.
Shortly after the invention of asymmetric cryptography, the ‘certificate’ was invented which was basically a signed public key with some metadata. This gave rise to that very powerful industry, PKI, where they made you believe that you needed them as an ‘issuer’ to be trusted.
Well, #nostr breaks that all apart, because the ‘certificate’ become part of the network, where every event (especially kind 0), becomes its certificate. If you need to graft of extra trust you can do so with nip05, and other yet to be specified trust schemes where an event (certificate) can be countersigned by another party or cross-validated against another source.
So in a nutshell, what does #nostr do? It breaks apart our current notion of a certificate and makes it part of the network as relayed events that are signed and uncensorable.