That's already possible today yet there are still people who don't which is why a more general solution for the screen reader is needed rather than requiring every site developer to do something special.

We shouldn't create general solutions for people building software poorly. We should help people build software better, in this by helping to promote the use of a11y specs.

This is actually exactly where model providers could be doing some good. If they said a11y is the way for LLMs to interact with the web and helped push developers to docs, tutorials, etc the web would be better off. Google did effectively just that with HTTPS, they told everyone use it or lose SEO value rather than slapping some solution on Google's end to paper over poor security practices.