Yeah, I disagree with that part as well. I think it’s fine for servers to store the content and provide endpoints for specific queries/sorts, and expecting the clients to have all the posts is a tad extreme.
In this case, yes the data needs to live somewhere, but that’s the nature of having data be retrievable.
Nostr does some interesting things! What I mentioned here is actually just the identity part of what I think could be a significantly improved version of the fediverse. I have ideas on how to support subreddit style communities and decentralized moderation and things like that that make the whole idea a bit different from nostr.