The problem with solutions like Nostr is that users don’t own their data. Relay operators do. Once you post data to a relay, you are giving ownership to them. They decide if it lives or dies, not you.
Note that this is at odds with a school of thought in Nostr that says each different niche app or niche interest should use a different relay.
Your suggestion would be a different way of thinking. Primarily one that is focused on maximizing different event kinds for each niche use case rather than having less event kinds and more single-purpose relays.