Not doing requests via javascript still works. And for quick and dirty stuff where you don't care about how things look and feel it's a perfectly valid way of doing things. A lot of developer tools fall in that bucket. And a lot of developers are in any case a bit challenged on the UX front anyway so there's a good argument for not using too many ways to shoot at your feet. But having every request wiping the current page, scrolling to the top, etc. can be a bit jarring as a UX as well. And there's the whole round trip latency for fetching pages too, which can be noticeable.
In other words, if paying customers are involved you probably should not go there. Mostly people expect things to look and feel nice and have some designers involved with the whole thing.
End users don't care about any of this of course. They also don't care if the app is native, a webapp, or something you could have hosted on geocities 25 years ago. But they do notice if things look dated, crap, or otherwise a bit meh.
They especially don't care how things look under the hood. The whole notion of semantically pure HTML, vue vs. react, and all the other nonsense web developers obsess about. It does not matter to them at all. You could use divs for every freaking HTML element and they couldn't care less. Or render the whole thing with some native UI toolkit to a canvas (which is an option these days). As long as it does the job.
You don't have to do a SPA. But you kind of do have to deliver something that works and looks and feels nice. With WASM, we are kind of getting a lot more ways to do things. The whole game of working around browser quirks and limitations with dom trees, CSS, and what not is not necessarily the way of the future.