...which is a simple consequence of Windows people not being used to polyvalent software. You're putting horse before the cart.
The comment I'm responding to says that progress bars in the terminals, and that TUIs in general are an accessibility nightmare.
Are you disagreeing? Are you claiming that it's a solved problem? Would you mind elaborating on what you think can be done to solve this?
The bulk majority of applications people use today are not "thoughtfully designed with native OS controls". Sprinkling some ARIA labels around is better than nothing, but the experience itself is extremely limited and is not on-par with what those people deserve.
I'm talking about Javascript/CSS-heavy websites in a web-browser, computer games, or software such as Blender/SketchUp/Google Earth to name a few. ARIA labels aren't good enough here - we would need to develop an entirely different interface to accomodate for each individual accessibility scenario. You can imagine a blind person and a deaf person using entirely different versions of Blender, each built with a different interface accomodating a specific disability.
I think its clear from your post that you have never dealt with the visually impaired or even explored accessebility options of iOS/MacOS/Windows. We have working accessebility for all applications throughfully designed with native OS controls.
Having separate front ends will never happen, most businesse sproduce a single bloated JS app that crashes equally on all platforms.