How are you supposed to "less JS" your way out of that?
I thought the 'if the level of interactivity basically amounts to a form' of top-level comment sums it up nicely. Many are SPAs for the sake of it, similarly to packaging a website as an 'app' but not doing anything native, offline, or that really warrants it being its own app at all other than getting homescreen space on iOS.
(Totally off-topic: I can't believe Apple still doesn't let you organise that however you want. It's sort of a small thing, but also so in your face, by far the most immediate turn-off to me of iOS.)
How do you compare "fast" between "my journal entry today" and "Photoshop on the web" using one set of metrics...?
Indeed, I’ve seen higher NPS scores when it’s slower… the user feels like they are paying for more.
One essay on this topic… https://medium.com/young-coder/the-future-web-will-canvas-re...
I spent much of the last few years working on such hybrid apps (DOM mixed with graphics techs, with clientside UI and state combined with server-side with and persistence, etc.).
The DOM has never meaningfully slowed down for me, even with CPU throttling or testing on old laptops. Canvas has, especially in some builds of Firefox. Certainly for rendering graphics canvas or WebGL are better choices, but it's not a performance magic bullet for all apps.
More often than not, the performance bottlenecks are just some bug of ours (a poorly implemented search algorithm) or an unoptimized query somewhere.
No modern web app needs to be just one thing or another. Even if you're operating almost entirely in canvas (like a map) there's still a ton of Javascript (open layers, leaflet, mapbox-gl-js, etc.) that you need, along with being able to use the DOM where it makes sense (reusing buttons, alerts, etc.)
Canvas is also really hard to make responsive. CSS evolved alongside the devices and has first class units for all that. Canvas doesn't have those easy abstractions and having to virtualize your UI without CSS-like helpers (much less things like flexbox or Bootstrap) makes it hard to make standard UIs too. HTML still has its uses for now, though arguably React and other abstractions make it much less important.
Games and maps are just an extreme version of that, but other examples where clientside DOM apps with heavy JS can still be faster (compared to old school server-side HTML) and easier to work with (compared to canvas) are email, e-commerce, ebooks, dashboards, chat, forums, video tubes, search and filtering, galleries, documentation, project management, etc.