So reading the github page this sounds basically like a variation on RSS. There are a number of web servers that host content (either for free or for money) [called relays]. Clients download recent posts Identity is based on public key, allowing users more control and the ability to easily change relays. So is RSS + pubkey based identity the right way to think about this?
Relays have to figure out how not to get smashed with too much data. I predict they will require an account/login at some point. But you can post to multiple relays and drop relays that don't serve you well at any time.