DRM isn't magic. It's still bound by the browsers' security policies, and those policies do not allow tracking by one domain of activity on others that aren't opting in somehow. Extraordinary claims require extraordinary evidence, and my pre-existing hatred for Elsevier isn't evidence of them having capabilities that would make the NSA drool.

If students were regularly installing a native app or a browser extension, the tracking claim would make sense, but neither you nor TFA have suggested a valid mechanism for the supposed tracking.