A very good point. I share a lot of puzzles and tech-notes on my blog. It might appear as a teaching tool to some but for me it is a great learning tool. An idea, a problem or a solution to a problem might exist in our mind in a confused form. But once we have to put it down in words for a larger audience, one has to re-think of the whole idea, problem or solution in a manner that can be expressed to a larger audience. This usually involves re-learning the idea in a simpler way.

In other words, I end up learning a lot in order to maintain a blog. The D-K effect won't bother one if one accepts the fact that a good blog helps you learn as much as it helps your readers learn. It's more about learning together rather than one person trying to teach other.