If you handle all interactivity server side so that the user can’t do anything at all without a round trip, sure. It’s just a terrible app for users with latency/patchy connectivity. As soon as you try to mix in slightly nontrivial client local state and transforms it becomes the most retarded JS imaginable.
This is the common misconception of LiveView coming from the JS community. LiveView is JS. It has a whole optimistic UI layer that solves all of the problems you cite. The UI from state updates coming from the server or the client doesn't matter because the reactive UIs of SPAs still require data updates from some remote source. So if we're talking about latency that latency is going to exist for all application types.
Where did I say it’s not JS? I said it becomes the most retarded JS imaginable. I have used the “whole optimistic UI layer”, hooks and commands. What happens is local diffs have to fight server sent diffs, at every level, resulting in more tangled logic than jQuery apps. This does not happen when you merely have to merge state and the view is a pure function of state.
