people do not trust the entity creating the technology

Similar APIs for validating native apps in the Android and iOS ecosystems already exist.

WEI provides a way for a browser to prove it is working as a website operator expects, and hasn't been manipulated

However, "abuse" is not specifically defined.

publishers have a want for their ad-based business models to work, and they thereby would like to have a way to require users to only use trusted browsers that will comply

The concerns raised include: potential violation of EU data rules; all web interaction would be subject to attestation – something Google explicitly rejects; barriers to new browsers; general distrust of Google; worries about DRM for the web; possible limitations on ad blocking; and more.

The stated purpose of the API is to address various long-standing problems on the web: social media manipulation and fakery; bot detection; misuse of WebViews in apps; bulk web hijacking and account creation; cheating in web-based games; compromised devices; and password-guessing attempts.

"If websites are going to require 'this is proven to be one of a small, trusted set of browsers – unmodified from their original behavior – that we believe will, in fact, show our ads to a real user,' then the bar only goes up for building a new web browser."

it's turning the browser from a User-Agent into double agent working also in the interest of advertisers and other corporate players

A framework for enabling publishers to make their customers their enemies is a framework for profoundly screwing the pooch.

Some in the internet community fear this is the end of the web as we know it.

Googlers have proposed a way to determine whether browsers can be trusted, as a defense against criminal fraud and other bad behavior.