People like services tailored to them but worry about the data this requires. A set of techniques aims to offer both, by doing more personalisation on the device, learning from groups rather than individuals, and limiting how much personal information is gathered centrally.
The goal is useful, relevant experiences that respect privacy, and regulation and public concern have pushed providers in this direction. There is a genuine tension, since richer personal data can mean sharper tailoring, so these approaches involve trade-offs and careful design. They reflect a shift toward treating personal data as something to minimise rather than hoard.