But as systems become more aware about the profiles of their visitors - it will become easier to ascertain who the specific individual is that is accessing your site. In some cases, this is already a possibility.
Now imagine a marketplace where Google, Facebook (or somebody that can connect an authenticated user to a digital "fingerprint" of their machine based on browser metrics, installed fonts, ip address, etc.) can answer the "who" question for partner sites willing to buy that information. Visitor-identification as a service.
Is this not exactly what Facebook, Google, and Twitter do with their tracking cookies? They figure out what you are interested in based on analytics regarding the sites you visit (obtained through multiple different methods), then sell that data to advertisers.
They sell access to those people. They don't provide specific identity information about those individuals. The Facebook example I posted shows how somebody was able to specify granular-enough parameters to focus on one individuals, but this type of targeting wouldn't work for everyone. I can imagine a day when this type of targeting is offered more-proactively.
No. Tech companies generally do not sell your data. They use your data internally to figure out what ad categories to show you. Advertisers can specify that they want their ads shown to people with certain interests. At no point does data about what you do on Facebook leave Facebook's control.
Having a email-specific link is not aggregate data; that can potentially be used to identify the user. Aggregate data would be a campaign-specific link that doesn't identify the user, such that a click from any person looks equal.
In double checking, at least it appears that they don't do this for some of their mailing lists; the mozillians.org stuff appears to have unmolested links.
I think that's dependent on what is stored. Sure the link enables them to capture a whole lot of data, but if an agreed standard of 'tracking data' was all that was stored. I think that would be an improvement.
EDIT: Similar to how we capture credit cards. Often the provider could capture and store everything, and publish it online if it liked. But generally (due to law, and standards) they are either passed off to a payment provider or stored with a certain level of security.
I don't think it is necessary in this case for Mozilla to even be in possession of transiently-non-aggregate data, though. If they want to analyze click-through rates or whatever, they can have URLs that are constant across users and not lose any data. For credit cards, the payment processor must have the unique card information, so collection is warranted in that case, even if they are never stored.
That is: since I have no insight into what happens to the data once it reaches their servers (outsourced to an external analytics platform), I object to them collecting it unnecessarily in the first place. Storage does not come into play, since while I trust Mozilla I don't trust the third-party, no matter how much Mozilla claims to have vetted them.
Perhaps analytics needs a standard for how they are stored (i.e only store aggregates, not individual records)