Ya I’m also not sure about this. I’ve done front-end desktop development, things like QT, Java Swing, WPF, Flash and Silverlight.
The dependency issues and challenges come from the browser space in my opinion, being a competitive environment, vendors took a long time to play along, and you always need something that can work with the browsers. And that prevented a lot of normal evolution. People competed for JS standards heavily, creating many standards that now need to be reconciled.
I think another issue is how far web UIs have gone compared to what the initial design of the web thought it would become. Now with SPAs, we’re very far from static HTML/CSS with a little bit of interactivity from JS. So it’s grown really fast, and in ways that weren’t really planned for.
Only recent JS UI toolkits like React, Vue, Angular, etc., I think are starting to rival the traditional front-end environmentz, by bringing back grid layouts, UI components, etc. Before that, it was really hard to build a proper reusable and extendable UI toolkit. And even now, you have the competition at play, with some toolkit being built over React, others Vue, etc.
Before that, the web didn’t really have a UX toolkit, it was mostly text and images in tables, with forms as input.
While I say all this, I like where things are ending up. In some way, this competition also pushed forward the innovation. Some desktop toolkit with their OOP and imperative heavy design are showing archaic in comparison. And the renderers and interactivity that web browsers has achieved is really impressive, with a push for resolution independence, vectorize graphics, GPU acceleration, support for screen readers and all that. So in the end, I think it’ll end up better, and already is showing signs, which is why some people now are bringing the web UI kits to the desktop. That said, the road is rough, and full of breaking changes and competing standards.
Oh, and not to forget, UI toolkits didn’t used to need to be bundled with each view. People would get their app delivered to them through a download/install, a CD ROM, etc. Or the OS would have the toolkit pre-installed. So the whole complexities around bundling and bundle size is another thing that makes web front-end way more challenging.