[contravariant]

The hidden assumption here is that things go well if and only if (you think) you understand all the factors that influence your metrics, can do experiments and are prepared to use fancy statistics.

Which I reckon is a bit iffy. Special relativity was thought out well before any experiments to test it were feasible, and if understanding everything that influences your metric is a prerequisite then you can blame all failures on insufficient understanding without having any way of knowing when you have enough understanding.