Lilia at Mathemagenic relates finding a quote from Edwin Schlossberg, "The skill of writing is to create a context in which other people can think."
For Lilia this inspires thinking about some of the philosophy in KM, particularly the discussion of knowledge vs. information. (Go read.)
For me, I think this has everything to do with good communication. If I can speak or write or draw well, then I have a much easier time of transferring knowledge to my audience. This means I have to know and understand my audience and their basic approach to the world.
I had the pleasant experience with tutoring recently, where I was able to convey a method for solving quadratic equations to a 12 or 13-year old girl who has been struggling. The next week, she came back and showed me that she had been practicing what I taught her. Good for her! I was able to give her tools that made sense, based on her current experience with that level of mathematics. (This week, I get to find out how she did on those tests.)