Yeah, as I understand it the idea is that instead of making the server-side complex and the frontend code complex, you retain as much complexity server-side as possible and treat the browser as just a hypermedia renderer.
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
Right. But, hypermedia systems doesn't go far enough. It can be even simpler then that.
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.