Because the tooling has been here for decades and it works damn fine. No need to trash the frontend with ever changing piles of dependency and build nonsense.
when? View code in the back-end always looks like crap and never able to achieve the interactivity the front-end can. People wrestling with it was the reason SPA was born. There was no dictator forcing people to move on from such "awesome" working "damn fine" pipelines to modern front-end for no reason.
That's probably the fault of the people writing it. People can also write crap looking code using frameworks too.
> and never able to achieve the interactivity the front-end can.
That's what small sprinkles of javascript is for. You don't need incredibly beautiful interactivity in every pixel.