Sure, but the browser is fast and rendering HTML so why stream anything else? Why stream javascript + json to build html. You're adding a bunch of marshalling that doesn't need to be there.
If a part of the page needs to change, the server figures out what it should change to and sends that page fragment.
At least, that's my cursory understanding from reading https://hypermedia.systems
In a video game the "server" doesn't figure out what's changed (that's too much work) it just redraws the frame. So rather than the complexity of working out what has changed you can just send down the whole page again whenever something changes.
This gives you view = f(state) over the wire and has great DX. It's called immediate mode in games.
Here's a basic google sheets clone that does just that: