Social Networks and Privacy.

It's very often hard for social networks to draw a clear line reflecting the intrusion of privacy and maintaining user useful information.
Classic examples would be Facebook and WhatsApp, it's hard for Facebook to suggest friends without necessarily importing all your bio data simply to your national identification data, unless they used WhatsApp data, and at that point WhatsApp bleaches your privacy and Facebook intrudes into your privacy just by simply asking WhatsApp for your phonebook details.

With that in mind therefore it would mean that if your brother has about 16 phone numbers and you have 150 phone numbers, your brother will receive friendship suggestions from Facebook about 150, and you will receive 16 even when in real life you have never met the 16 and he has never met any of the 150. This is good if your new in an area or your village is smaller but when your village is a city your bound to have problems.

In otherwords it's only useful to gather information for internal consumption(determine relationships,social interactions, residence proximity,safety alerts,happening place alerts) rather public consumption(friendship suggestions,news feed filtration).