I think a little piece of that idiom is left out for the sake of making it a good sound bite. An expert can explain something to an eager listener. Would you be able to explain something you're an expert in to a patient lay person who actually listened and tried to ask the best questions they could?

It is an entirely different skill to educate someone with your expertise when you don't get their feedback (tv, radio, youtube) or when they don't want to learn (classroom teacher, office politics around bean counters). Those are two kinds of education and they are important skills all on their own but are in no way tied to other kinds of technical expertise.

If we were both working on a project that needed your and my expertise. If I understood that you had different sensibilities about social norms. If I respected those while asking questions about parts of your explanation I didn't understand. Would you be able to explain a detailed topic to me?