Back in 2009, I worked on a complex SPA using GWT. With GWT, you could pretend to know nothing about HTML/CSS by just using the ugly build in components, but none of the GWT users I met did that. Our app used a Model-View-Presenter structure, dependency injection, and event bus for asynchronous communication to let components know when their data had updated, plus UIBinder templates for defining the look of components (which are mostly just HTML and CSS). So although it was nicely structured, it was very much a web app, and the development experience felt pretty comparable to what I experience in React today.

XAML is mostly just a way to declaratively specify the layout and structure of UI components. Actually, I think it's just a declarative syntax for creating a hierarchy of object instances. If I remember correctly, the XAML and its corresponding C# file are both partial implementations of the same class, since .NET allows partial classes.

Now, I'm not saying that I think the current state of JavaScript tooling is the worst thing ever. But I do think that that some of the 2009-2010 era JavaScript frameworks provided a more sane and cohesive development experience. React and Angular are nice, but I also remember that in 2010 it felt pretty neat to create an interface in OSX's Interface Builder, and have it show up in my browser exactly the way I'd drawn it.