Many sites do this. They encourage users to give full access to their phone's contact list, and store all the data they get from it, then start building a netwo

Many sites do this. They encourage users to give full access to their phone's contact list, and store all the data they get from it, then start building a network of "people who know this email address/phone number", ostensibly so that when they finally convince someone to sign up they have a ready-made network of recommended "people you may already know".