Having developed in all of those (Borland C++ Builder which is the same as Delphi except not OO Pascal, QT, and web)...

The amount of power CSS gives you over the precise look of the app at different aspect ratios gives an awesome amount of control over what the app looks like on any screen size.

Also, things like wrapping of elements from one line to another work very well in CSS/HTML, especially when dealing with interactive rich text. For example, in some UI libraries (iOS comes to mind) making a line of text with a clickable image inside of it that wraps when the text gets too long is frustratingly difficult but in HTML it is a piece of cake.

With that said, the rich text editing choses for web are much easier to work with and more robust (IMHO) than the desktop equivalents.

Not to mention OpenGL rendering, vector graphics, loading of assets from the network are all built-in. All of which can certainly be done from a desktop environment but the tools to do so are not as mature.

.NET makes a lot of strides in this direction. But if you're going to include the .NET runtime with your distribution it will be almost as large as Electron apps.

Then there are animations which are easy in web technologies. And which UX designers are starting to realize is an important aspect of good user experiences.

Can all of this be done in QT? Absolutely. But all of it is out-of-the-box with web.

As far as the RAD tools from the 90s? Not even close. Albeit Blend is nice. But tools like that do exist for web, just not for desktop UI. I'm sure if web tech becomes more common in desktop UI the tools will come.