This mainly looks like a push to remove even more user control over tracking. The spec says that the browser can return 'random' data, but I suspect that Chrome

This mainly looks like a push to remove even more user control over tracking. The spec says that the browser can return 'random' data, but I suspect that Chrome won't let you do that, or at least not for long. Instead of the user disabling third-party cookies, every single page author would have to set a new HTTP header to have their page excluded from the machine learning. It also looks like a massive GDPR pitfall. Say you track conversions to a campaign, and track what "cohorts" a user entered your sales pipeline through. The moment you connect this data to the customer, it's personal data IMHO. If you operate in Europe, the user should be able to retrieve/delete the data, and request it changed if they say it's wrong.