I don't agree with that;

I think if generic clients had a way to parse "unknown events" in a way that makes sense of them, the experience can be perfect.

Think about a picture; someone shares one as a kind 1. People comment on it. A discussion ensues. You want to be able to see what your follow list is discussing around that picture.

A song, a list, a highlight, an item for sell, anything is the same thing; if done publicly, it should be done in a kind 1. That's the cool thing about nostr; data flows unencumbered, not siloed.

What we need is a way for clients to be able to render and discover handlers for unhandled kinds.