Phoenix Live View[1] fits the gap between server rendered HTML pages and JavaScript rendered front-ends. If you’re after a responsive web UI without needing to learn so many disparate frameworks and technologies it could be a good fit.
Its technique is not new, it's just server-side rendering via websocket and DOM patching (Morphdom is also very old)
> not appropriate at all
"At some" would be appropriate. Pretty much typical CRUD (real world) that needs to fire requests to server anyway (e.g. form, business logic validation).
The only reason not to use it _right now today_ is it's not 1.0 yet.