As the article and comments mention, writing forces you to understand your material really well. I'll offer another perspective: it's useful to approach topics

As the article and comments mention, writing forces you to understand your material really well. I'll offer another perspective: it's useful to approach topics from a less knowledgeable perspective. The beginner's perspective exposes a lack of information on the topic, especially if the topic is usually covered only by experienced folks. It's also a great way to gather feedback from others who know more about the topic, aiding both you and anyone who reads the resulting discussion/follow ups. The key is to be transparent with knowing about the topic and explicitly soliciting feedback in areas where you have low confidence. This is the part many armchair experts miss.