Assistive technologies will still work as the browsers implement platform's assistive APIs.
Automatic testing will still work because a developer isn't going to add restrictions to their own tests from their site. Unless they are testing if a captcha gets shown from an unsafe environment.
Archives, search engines, and spiders should already be respecting robots.txt. Site owners can already block those things if they don't want their site crawled.
>This means that no single party decides which form-factors, devices, operating systems, and browsers may access the Web.
The proposal allows anyone to become an attestor. There would not be a single attestor who you would have to prove your trustworthiness to.
And websites get to choose which attestors they accept. For an attestor to do what they are expected to do, they need control of everything from the TPM up. This means there will be effectively 3 attestors - the major operating system vendors.