The standard root cause hunt runs on federation. The metrics live in one tool, the traces in another, the deploy history in the CI system, the config changes in a cloud audit log, and the identity events in a fourth place with its own clock and its own retention. An engineer under incident pressure has to join those sources by hand, and the joins are exactly where the analysis breaks. We catalog the manual techniques in log correlation techniques, and the honest summary is that they are compensations for an architecture that separated signals which belong together.
The result is familiar: the incident is mitigated by restart or rollback, the true cause is never established, and the same failure returns wearing a different symptom. A postmortem without a causal chain is a guess with a document number. The fix is not a smarter dashboard, because dashboards are snapshots of individual silos. The fix is putting the signals in one place with one clock, which is an infrastructure decision, not a tooling one.