Every bit of interactivity/ reactivity that product wants to add to the page feels like a weird hack that doesn't quite belong there, polluting the simple, decl

Every bit of interactivity/ reactivity that product wants to add to the page feels like a weird hack that doesn't quite belong there, polluting the simple, declarative model that your views started off as. This doesn’t need to be the case though. There have always been server-side frameworks which generate the client-side parts for you automatically, so you can mostly avoid writing any javascript even for the interactive parts. Check out rails/turbolinks/stimulusjs (used to build basecamp and hey.com) or the TALL stack (increasingly popular in the php community) for modern day examples.