Because you learn something about the nature of the people on that list. Thus, a telephone number tells you they have enough money to have a phone - a small but significant piece of information. Other much more detailed information such as the type of property they live in, the number of transactions you have had with them, their ages, and so forth all build up a picture of them. The accuracy of this picture will determine your ability to communicate effectively. The closer you can get to picturing the real individual, the better a job you will do - which is why the database is so important.
Perception is strong and sight weak.
In strategy it is important to see distant things as if they were close and to take a distanced view of close things.