The document discusses the importance of measuring customers rather than devices or cookies in web analytics. It emphasizes that customers are not homogeneous and should be analyzed and treated according to different segments like fans, regulars, and occasional visitors. Tracking unique customer IDs across channels allows companies to better understand customer lifecycles, attribute marketing ROI, and identify cross-channel opportunities. Mobile analytics presents new challenges to connect app usage to revenue that can be addressed through a holistic cross-channel view linking customer-level data.