Can a publisher demand "user information" in exchange for reading an article, even if it lists 1500 trackers, even if it's part of the contract? No , GDPR forbids it.
That's the gist of the matter. Private information is not tradeable, therefore it's not really property, and certainly not owned by the users since they can't sell it for goods they readily want to acquire.
The clause you quote only applies if the private info is necessary for the service rendered. GDPR considers advertising optional, despite the fact that it's crucial for the survival of websites.