Abstract
Personalized systems increasingly shape what people consume, watch, learn, and purchase at global scale, yet they are typically optimized for engagement and short-term user satisfaction while their broader environmental and societal effects are rarely accounted for. This creates a structural tension: systems designed to increase interaction are incentivized to drive activity and consumption, while sustainability goals often require reduction, moderation, and efficiency. In this paper, we argue that this tension is not incidental, but follows from how personalization systems are conceived, optimized, and evaluated. We structure this tension into a set of recurring conflicts, including objective misalignment, efficiency–impact trade-offs, system-level externalities, and ecosystem blindness, and show how they manifest in real-world settings. Rather than proposing a single solution, we argue for a shift in perspective. Instead of optimizing isolated metrics, personalization systems need to be understood in terms of how they interact with the systems around them and the behaviors they induce. Our goal is to make these interactions visible and to provide a basis for developing systems that better account for their broader impact.