Most importantly, Pubky cryptography is objectively better than Nostr. Both harder and faster... Pubky's Ed25519 will always be faster than Nostr's Scp256k1 and this translates to a 4x speed advantage, even up to data payloads of MB/GB/TB. Pubky's core architecture is built on Public Key Addressable Resource Records (Pkarr) i.e. Kademlia, whereas Nostr relies on relays that claim to be decentralised. Plenty of other reasons too.