I think you're describing a specific app more than a protocol. I think it would be cool, but at every point in your vision there will be people wanting to do something slightly different, and I think it's nice that the protocol is flexible enough to support these things. And we could just say "no, that is not Nostr", but then people would do the things in a worse way that isn't interoperable and creates centralization that may be fatal in the long term (it is happening everywhere already, but much less than it would if there wasn't a culture of standardization and interoperability around). Maybe you don't care about any of that, but I do. Anyway, Nostr can be used just like you described and that doesn't hurt the other use cases, nor vice-versa (maybe a little bit, but that's inevitable). In any case, I personally think the vision you describe (even if I think it's cool) would have much less appeal (can you imagine? even less than today!) than the current idea of a multimedia everything-interoperable Nostr, and, given that Nostr needs 10000x more people than it has today in order to be useful in any way to the world, restricting Nostr to that (even if it was possible) would be a bad move.