In my experience server side rendering becomes really messy once you hit complex state management. Shuffling shit between pages, persistent vs transient state, handling reload/resubmit logic, validation. It works for simple stuff but even then I think once SPA tech matures more (ironically even after all this time I think transpilers/bundlers/package managers in JS still have a long way to go to get out of the way and frameworks are still far from optimal) anything that's not a web page should handle UI logic on the front-end.
All code, across all paradigms, frontend, backend, low level, high level, whatever; all code becomes really messy when you have complex state management.
The solution in each of these cases is the same, though. To simplify the state.
In general, I think a lot of the pain in web development comes from attempting to have shared mutable state between backend and frontend. Shared mutable states are almost always messy. You can get around that by pushing it all to the frontend, or pushing it all to the backend. It's when it's straddling both you're in for a headache.
I agree - but you can't simplify when your tools complicate - in the sense that they intertwine different concerns. As soon as you're not dealing with trivial apps "pushing it all to backend" isn't really an option if you want good user experience - and then you'll have to have logic on frontend as well. And that's where the pain comes.
WHAT??? Okay I am going to bite, state is managed by the browser and then SPAs came along and tried to hack the state management ever since. I remember creating SPAs in 2004 when it was called AJAX and there was the debate of HTML or JSON over the wire. The biggest issue was back and forward buttons, even today that issue is not solved very well by SPAs.
The issue I have is we had a great idea to refresh parts of a page with AJAX and then we went overboard and tried to move the entire application to complex frameworks which add more problems then they solve. We became so scared of screen rendering we avoided at all costs. This is bad UX as users actually get good confirmation that something has happened when there is a screen refresh.
