Part of why I think that needs to be a legal requirement is to prevent debates about whether management knowingly sabotaged a competitor – proving intent is much harder than simply showing negative outcomes for users – but the other is to keep web standards meaningful in a world where Google has successfully pushed most people to use Chrome: if a regulation required cross-browser testing and use of W3C standards (i.e. if Firefox implements the standards and reCAPTCHA fails, Google has 7 days to fix it or shut the service down until they can), they can’t push key functionality into Chrome-only APIs.