The web was designed for interactive documents,not desktop applications. The layout engine was inspired by typesetting (floating, block) and lot of components only make sense for text (<i>, <span>, <strong>,...). There's also no allowance for dynamic data (virtualization of lists) and custom components (canvas and svgs are not great in that regard).

> building for modern desktop platforms is horrible, the framework-less web is being used there too.

I think it's more related to PM wanting to "brand" their product and developers optimizing things for themselves (in the short term), not for their users.