I don't want that. I don't want to care about screen readers (unfortunately I have to). I want a system where I can pick well-defined rules and then css can style it, screen readers will understand it, automations can parse it, keyboard navigation is free.

Obviously thats not what we got, but I feel like the set of established UI patterns is manageable enough that it could be built.

A great example is the new <select> styling that developers styled in all kinds of creative ways. Now give me that for comboboxes, trees, data-grids etc...

There are already well-defined rules, you just don't like some of the rules, e.g. you can't (today) style <select> options. Keyboard navigation is free as long as you follow the rules about which elements are focusable.

You shouldn't have to care about screen readers the same as you shouldn't have to care which browser someone uses but you always have to care about people; people who can't see or hear what you create, people who can operate a keyboard (or keyboard-equivalent) but not a mouse or touchscreen, people who can use a touchscreen but not a physical keyboard, etc.