The main browser API is pretty stable, all things considered. It's just that people can't seem to stay put on a given design, instead trying everything under the sun.
When you have something like SDL which is at it's third version at 27 years old, I'm very doubtful about the culture of NPM/JS world. A closer example is jQuery which is also in its third version at 18 years old.
True, the browser API might be stable, but the best way to build stateful client applications is unstable.
It's a constantly improving and experimental domain - not just on the web but also the desktop and mobile environment.
Next.js is a good example since it (and its competitors) are a natural iteration on top of SPAs where you want the first request to the server to also inline the initial state of the SPA to remove the double-request problem.
But you pay a huge price trying to live on the edge like that, and when you run into issues, it doesn't make much sense to call that the state of web development since you could have used boring server tech or even a boring React SPA which also hasn't changed much in a decade.
When you have something like SDL which is at it's third version at 27 years old, I'm very doubtful about the culture of NPM/JS world. A closer example is jQuery which is also in its third version at 18 years old.