In the example I used to open this section, I start with James Kirk who has an email account email@example.com and joined Facebook as James Kirk using that email account.
Now, suppose James Kirk only uses his gmail when he is corresponding to people he knows.
On Facebook he calls himself Captain and uses JamKik@crapmail as his email.
Other sites he joins as JTK or Tiber or CapK and uses different email accounts.
So how is James Kirk’s information, gleaned by the data sniffers on Google going to help them on Facebook?
How can what he posts on Facebook be linked to anything but his crapmail account?