I see so many websites trying to implement their own UI behaviors and getting it wrong, not scrolling smoothly, showing a modal window partially off screen in certain scenarios, preventing you from zooming out on a smartphone while overflowing the text outside of the screen, menus that are either not touch or mouse friendly, etc.
Giving UI developpers only html and css is like telling a graphic designer: all you need is microsoft paint, you see you can change the color of each pixel to whatever you want, total freedom! Yeah... No.
If you want, you can make a framework on top of it that will behave like a desktop UI framework with standardized elements and behaviours. There are plenty of such frameworks actually. But not having to use such a framework is nice.
Besides, the current browser environment has been historically heavily optimized for websites, not desktop apps. If it became a popular choice for desktop app UI we'd have developed more appropriate features for that use case.
On the web the role of desktop UI frameworks is distributed between third party frameworks such as Bootstrap which is great because those are optional.
I haven't worked with the windows frameworks you mention to compare directly to them.
Tables are just unstyled boxes with an alignment rule. Not very high level.
Buttons are provided by the host OS, HTML and CSS have nothing to do with their default style or behaviour, and if you start styling them you basically revert to working from unstyled boxes.