The way I see it is building apps somewhat similarly to SwiftUI is actually a pretty good idea. If you have established rules for how each container expands or fills its content you can build a great web app development experience without getting down into css and html explicitly. Just Vbox container Hbox container text container etc. I can certainly see a niche for this as it is a different style of UI development.
I’ve never been great as a UI designer so doing it in the traditional web stack has always been even harder but I’ve found that with SwiftUI I can usually get 90% of a good look very quickly.