It seems odd to bring in Java applets and similar technologies to the discussion when the original point was that web development shouldn't need a build step. And isn't the whole point of SPAs to implement local interactivity? I.e. treat the client as a separate application (just like you would with an applet) and move session logic out of the server?
If anything, I think it's remarkable how far we've graduated from that point: many features components and features that we used to have to build by hand are now directly implemented in the browser; Javascript is significantly easier and nicer to use, even without having to apply a build step (even just splitting scripts into separate modules is now supported natively!); and features that previously required potentially insecure plugins to be enabled are now controlled by the browser, giving users much more ability to control what their browser is doing or not doing. Even if you do want more complex development with build steps, with tools like Parcel and Vite, that's usually pretty simple at this point (certainly simpler than the last few Java builds that I've seen).
It seems like you're complaining that everything is worse now because it's possible to have stupid amounts of complexity these days, but it's also a lot easier to have no complexity at all.
