sure urbit is interesting, there is many interesting projects, they all never take off for a variety of reasons, for p2p social they generally just dont work, look at ipfs it just runs poorly and social built on it even worse, one of the best p2p protocols was hypercore which has become holepunch which is what keet.io is using, the dev being done on it is determined to solve p2p for most uses and seems to be getting there such that nostr apps should look at using it

nostr is succeeding now because all these different apps can talk to each other and any new app has an established user base and content, and its censorship proof but only for text