The hal-forms specification seems a great approach to building dynamic, state, driven forms but there seems little adoption in front-end libraries (react etc.). rwcbook.github.io/hal-forms/

I used to believe in this approach until I noticed the browser does a pretty good job with forms natively

It depends on what your target is. If you're just wanting to build a website with a few forms and otherwise simple pages, absolutely right. But what if you want to target other things? The same API response can also power Android, iOS, etc to tell them the correct way to work.