That is a ”controlled component” model which is bad for interactivity, especially text inputs.

If every keypress triggers a state change and rerender, the UI will be slow and things like focus management become complex issues.

Without a rerender, it must now use a reactive binding to update the field value.

If you don’t want to update state on every keypress, your component must be uncontrolled, store its state internally (in the DOM) and update it to a parent store e.g. when the user stops typing (debounced) or moves focus out of the field. These are not trivial things either, and as a result, components get more boilerplate to handle the UX complexity. And of course, there are now UX pitfalls.

Indeed, these are reasons why reactive patterns exist. Now, if they just managed to abstract away the tedium.