While RDD is a thing, the root cause is the stakeholders' requirements for more sophisticated and complex sites (whether smoother page transitions, more intricate effects, incessant demands to spy on every user interaction etc). It became harder and harder to do all this with server rendering and a rat's nest of jQuery. JS frameworks arose to meet these requirements and became an industry standard, and developers responded to market demand. It's all gone too far of course, but the stakeholders were as much to blame as anyone.