It's not simple. I made multi-page forms with dozens fields where your suggestion would lead to intangible mess of spaghetti code - I know because I worked with the web way before React. Even with the best coding standards and a team of seniors it's just too hard to maintain - and seniors usually don't write forms.
I really don't want to go back to the jQuery days. You do you, but don't say it's easier - it really isn't.
BTW you can just use Preact if you're worried about the bundle size. I do that, it's perfect and just a little performance impact, usually not visible in small apps.
Oh that's interesting, multi-page forms are actually my least favorite form use case for react.
I reach for a state machine whenever possible to manage the complex flow of the multi-page or multi-step form, even if react is still used for custom inputs.
But it's not that necessary in my case, my forms are usually not complex statecharts, just a lot of individual and largely decoupled complex form controls - multiselects with rules, map pins, tag inputs with autosuggest, data grids etc.
I really don't want to go back to the jQuery days. You do you, but don't say it's easier - it really isn't.
BTW you can just use Preact if you're worried about the bundle size. I do that, it's perfect and just a little performance impact, usually not visible in small apps.