Identify Input Purpose requires form fields collecting common personal information, name, email, phone number, street address, to use the correct HTML autocomplete attribute value so browsers and assistive technology can recognize their purpose. This allows browser autofill to work reliably and lets some assistive technologies present recognized fields using icons or symbols instead of text.
Beyond accessibility, correctly identified fields also make checkout and signup forms faster for everyone, since browser autofill can only work as well as the underlying markup allows it to.