I think you're failing to understand that there are hundreds to thousands of functional applications out there that are not SPAs that are doing all of those things just fine. An SPA is not a requirement to be able to update values in a form, transition between page states, etc. The two options are not only Static Site or SPA -- that is the absurdity.
Making an entire application a single page load and then some API calls sounds attractive when your application is small to medium sized in terms of complexity. It runs into problems when complexity or feature count pass a certain point.
Making an entire application a single page load and then some API calls sounds attractive when your application is small to medium sized in terms of complexity. It runs into problems when complexity or feature count pass a certain point.