The player who asks to understand a decision is not automatically refusing to accept it.

Being asked why can sound like resistance when you are the one who made the call. Usually it is how someone tries to comply well rather than merely comply, and a person who understands the reasoning can apply it next time without being told. Treating the question as defiance teaches people to stop asking. What you get then is quieter agreement and worse work.

When someone questions a decision of yours this week, answer the question first and judge the tone later. Give the reason in one sentence. If the decision is not open to change, say so plainly after the explanation rather than instead of it.