WhatsApp largely shares data for the sakes of convenience and safety. It helps improve your “experiences” with other Facebook services, such as suggesting friends and content, personalizing features, and helping you make purchases. You can link your Facebook Pay account to complete transactions, for instance, or chat on Portal devices.
Other tie-ins are more vital. They help push “safety, security and integrity,” such as dealing with abuse and spam. They’ll also help WhatsApp improve its infrastructure and delivery systems, and help you understand how both its services and other Facebook products work.
There isn’t much detail in WhatsApp’s new privacy section, but there aren’t any shocking revelations, either. The chat service is outlining functionality you’d likely expect. Still, this is a reminder that WhatsApp is just one part of a larger Facebook ecosystem, and that your data won’t necessarily stay within the service — worth noting, even if your data won’t travel very far.