You are applying a one way arrow to events where in real life events do change state and can completely change UI (and functions) itself. Which makes imperativ

You are applying a one way arrow to events where in real life events do change state and can completely change UI (and functions) itself. Which makes imperative always the superior mode. What you described works only in super simple scenarios. Whink Web 1.0, when Javascript was used for basic form validation at best, and didn't change DOM that much.