How How most apps do it does it
Push notifications are not an accident. They are the engineered re-engagement loop. The app interrupts you when you weren't going to check, the badge count creates anxiety until you tap it, the notification sound trains a reflex over weeks. Every major social app — TikTok, Instagram, Facebook, X/Twitter, LinkedIn, Snapchat, Reddit — pushes by default. Email-driven products (Substack, Medium) push too, just through a different channel. The metric being optimized is daily-active-users; the friction being engineered away is your decision to not check the app right now.
Apple's own Human Interface Guidelines instruct developers, in plain language: "Don't interrupt the user — particularly during a time-sensitive or important task." The guidelines describe alerts as something that "disrupt the user experience and should only be used in important situations." Social apps push anyway, because the alternative — earning your re-visit through pull-quality content — is harder and slower and produces fewer sessions. The interruption is the product.
The harm at scale is named. The US Surgeon General's 2023 advisory on social media and youth mental health flagged the constant-notification environment as part of why teen depression and anxiety rates began climbing in 2012. Jonathan Haidt's The Anxious Generation (2024) names the same mechanism: a generation of kids whose phones interrupt their attention, their sleep, and their developing capacity for sustained focus. Adults pay too — every notification is a request that you stop doing what you were doing and turn toward the app instead.