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.