I work at Tlon so I'm biased, but I joined because I think urbit is the best way to get ourselves out of the local max of computing we're trapped in.
Email is a failure as a federated system (people on a tiny amount of centralized providers), the promise of the web as a decentralized place for people to interact p2p failed (FB, Instagram, etc.).
We're serfs operating accounts that manipulate our attention so that we view more ads on massively centralized systems controlled by companies that have their own incentives. Urbit is an escape of that. You can't fix these issues without fixing the problems earlier up in the computing stack, federated systems on the existing stack are doomed to always be relegated to a tiny hyper-technical niche. Urbit's design means it's possible to get the UX such that everyone could use it (likely most by a provider running the urbit for them).
Federated systems don't even really solve these problems for most users unless you run your own server (an even smaller subset) - you're just trading one dictator for another (and likely it's worse given how subreddit mods behave - mastodon is a good example of this).
https://zalberico.com/essay/2022/09/28/tlon-urbit-computing-...
http://moronlab.blogspot.com/2010/01/urbit-functional-progra...