Your phrasing is confusing. Why would the business want to deny services to a user who chooses to take personal responsibility over the data they provide?
Sorry if it wasn't clear. I'm suggesting that a business should have some right to deny service to a user who chooses not to participate in tracking, so long as it's made abundantly and plainly clear to said user that they'd be tracked, and that the user consents to that.
Based on my interpretation, the GDPR simply precludes that possibility.
I assume if you made a business where the user can sell their behavioral data for a service in return, and if the whole goal of the business was selling data in return for a service, then I would interpret the data collection to be strictly required for the business goal and thus legal under the GDPR (given explicit consent).
The official goal of Facebook is not "buying your data" but "providing a social network". Thus, targeted ads are not strictly necessary for providing that service.
I think the data must be actually necessary for the thing you're providing to the user. So if you're paying cash in exchange for data, that wouldn't be allowed, because you don't need someone's data in order to give them cash.
