Comment by lunar_mycroft

You have to manually write that out either way. In the SPA/reactive paradigm, you have to specify that multiple parts of the UI depend on the same part of the state, vs sending down those multiple parts of the UI from the backend.

I'd also argue that if you look at the interactions on web apps, you'll find the number of cases where you would actually need an OOB swap is more limited than you might be thinking.

This isn't just a hypothetical. I have written apps both ways, including porting a few from a SPA framework to a hypermedia based solution. It allowed me to sidestep several major sources of complexity.