Earlier quoted context omitted.
I don't care if advertisers know more about until they can actually identify who I am (name and contact info) and start calling me, sending me emails, and mailing me directly. Since it's not in Google's or Facebook's best interest to allow a direct connection between their advertiser's and users (if they no longer act as the proxy, where's the money?) I'm not terribly worried about it. I would like there to be more t…
Which they potentially can right ? If you see a random ad for a company on Google, click on it and then supply your email. Then they would know a lot more about than just your email. They would know every demographic filter they used to create that ad. That could be quite specific.
Browser fingerprinting is far more alarming: http://panopticlick.eff.org/
Let's say there's a SASS service you can tie into that has a massive database of browser fingerprint activity. Potentially you could get quite a significant amount of browsing history once enough websites are using the service. You can tie this to an email address etc. when a site requests a signup.