I mean he has a point. Things are incredibly complex now adays, I don't think most people have time to "understand the system."

I would be much more interested in rules that don't start with that... Like "Rules for debugging when you don't have the capacity to fully understand every part of the system."

Bisecting is a great example here. If you are Bisecting, by definition you don't fully understand the system (or you would know which change caused the problem!)