This is an amazing statistic and if you think about it, it does make sense. Taking the flip side of this statement below (which implies the privacy issues of such combined data), there are huge implications on the ability to do targeting with limited data:
It was found that 87% (216 million of 248 million) of the population in the United States had reported characteristics that likely made them unique based only on 5-digit ZIP, gender, date of birth. About half of the U.S. population (132 million of 248 million or 53%) are likely to be uniquely identified by only place, gender, date of birth, where place is basically the city, town, or municipality in which the person resides. And even at the county level, county, gender, date of birth are likely to uniquely identify 18% of the U.S. population. In general, few characteristics are needed to uniquely identify a person.