In case of any errors, notify the user, refresh the state .etc => This would all be done server-side and the client side would simply react automatically. The client side code in this case would have been minimal.
I don't think I'm diminishing anything. For quite a few years I was neck deep in React/Vue world. Now that I'm actively using LiveView, I can properly compare the differences between both approaches, cons and pros. For any new project, in the majority of cases I would pick Elixir with Phoenix LiveView instead of Elixir/Phoenix (backend) with React/Vue (frontend).