Nostr solved no “hard”, as in ByzGenP “hard” problems. Social media, or just messaging itself, is not a computer science problem. We have had open comms protocols like IRC since ‘88.

If nostr solved any problem, it was codifying a simple json encoding protocol that enabled arbitrary signed messages to be collected and relayed. It was simple, and allowed rapid development of web and mobile clients. It was extensible and permissive. Many people ran infrastructure for free to distribute notes via their relays. Because it was censorship resistant, a lot of the notes were spam.

Of the real world problems, not computer science, that may be solved using this nostr, these will exist in layers and extensions to the protocol.

I don’t believe social media is actually a problem to solve - it is what it is.

Nostr is not social media, it’s simply a protocol to sign and distribute and retrieve messages.