The big misconception is that the consent forms are only about cookies. They aren't - they are about data collection and processing in general, no matter the technical means. It could be cookies, but it could be IP addresses, browser fingerprinting, or information you manually entered for a specific purpose (delivery address to receive a package) and don't want to be reused for other purposes such as marketing or tracking. None of that can be communicated at the browser level unless you want to have a gigantic spec that encodes every possible use of personal data imaginable.