If your toddler replaces "why" with "can I play minecraft", it has probably expired (at least with regards to its job as a debugging tool) and you might consider getting a fresh one.
One of the commonly taught techniques for Root Cause Analysis is "five whys". Literally, just ask why up to fives times. Yes the Wikipedia page lists criticisms and yes, they include that sometimes 5 isn't enough, or that asking irrelevant whys or hitting the limits of your deeper knowledge or wandering into the wrong line of inquiry will all mislead you.
But I've had massively overpaid consultants at multiple companies explain to rooms full of adults that asking "why" can sometimes help you find the cause of problems.
