Somebody wrote something on a card and handed it to you.

A few minutes ago they asked what you are building, listened, and asked one question. When the answer was not obvious, they wrote down what they had found and gave it to you.

That was not a guess, and it was not them being especially sharp. The question came from a method that asks questions like it of every project, as a matter of routine. What happens when somebody is not signed in? Who else can see this? What happens when two people do it at the same moment? What was decided about it failing halfway? The finding landed because the question is a good one, and because nobody had asked it of your project yet.

Keep going and that is what you get: the same kind of question, asked all the way through, before anybody writes the thing, while an answer still costs a conversation rather than a rebuild.