I think teaching requires not only that you understand how to do something, but also what someone else's incomplete understanding is. You need to address the root cause as to why the other person's understanding is so lacking, like your examle with the tango dancer, instead of pointing out that a move is wrong and not giving the tools to prevent it. There may be many paths to reaching similar understandings, and a teacher needs to be able to tame this sprawling diversity. That's one reason why we don't just get blog posts or films that are exceedingly short, because if everyone could just understand a dry delivery of the core points instead of needing to think through multiple examples and reasons, we wouldn't be so pressed about teaching.