Downdetector is a survey, not a detector, and suffers from user confusion when a high-profile service is actually down, as users start reporting unrelated things

It also suffers from people reporting functionally related (but not technical related) things.

Any other service that interacts with Outlook in some way will create downstream effects in other services expecting Outlook to work normally.

Especially when looking constitutes reporting (Schrödinger's downdetector?) and people look at everything after showing up for one thing.