The Cambridge Analytica and Facebook story is a big deal. This has to be one of the BOOMs. Perhaps even the reason for the Bannon/Trump drama earlier.
This type of stuff goes back decades. Take a look at Vin Gupta. He is tight with the Clintons. He founded InfoUSA (later InfoGroup) and went on to found DatabaseUSA. Pre-internet/FB era the companies tracked everything about you. The biggest data compilers around are also the Credit Bureaus. How do you think they make their money?
Email is considered a unique identifier with FB. One company as an example, Constellation Media has database of over 1.3 Billion emails linked to their consumer data file. This file contains everything about you, over 200 different datapoints including behavioral data.
From any list, yours or theirs, they enhance with email identifier, which in turn matches to FB and even online cookies. Even if I know the behavior of a person or group, it can be expanded beyond to others all tracked with cookies.