Because in 21st century, not everyone likes a website with a lower-bar rendering experience… SPA or hybrid rendering is just plain better, but I get the point where time is limited for human being, so if modern frontend is hard to grasp for you, perfectly to stick with old tech. Pretty safe.
It is not for your end users, just for the developers building it because it has a better dev experience. As a proof of this try most sites out there which are built as an SPA vs the ones built with more traditional approaches.
Also, building SPAs is incredibly more difficult and time consuming, that's why most of them work like shit.
