When the system that monitors health becomes a participant in the system it monitors, observation becomes a failure vector.
Health checks consume the same resources they monitor, creating a feedback loop under stress
If disabling monitoring improves system performance under load — if health checks create the connections they're checking — if the monitoring system's failure mode is indistinguishable from the application's failure mode — the observer has become a participant.
Every monitoring system is also a system. Kubernetes liveness probes, load balancer health checks, APM agents, log collectors — each adds overhead that is invisible under normal conditions and catastrophic under stress.
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This pattern has been found in applications built by talented developers at respected organizations across every decade of software history. Its presence in a codebase is not a reflection of the developer who wrote it — it is a reflection of what that developer was taught, what tools they had, and the path that was easiest given what they were taught. The goal is not to find fault. The goal is to find the pattern — before it finds you.
Katie's Law: The developers were not wrong. The shortcut was not wrong. The context changed and the shortcut didn't.