(you may want to consider doing something similar for yourself!)
This article sums it up quite well, key points below:
1. Blogging can improve your communication skills
Communication and writing, much like programming, are skills honed through countless hours of practice. As you work hard at articulating your thoughts into words, you’ll find that the process ends up improving your ability to express yourself. And communication is key, almost regardless of your profession.
Over time, you’ll become a faster and better technical writer, who’s able to come up with an insightful essay or tutorial in just an hour or two.
Even better, you’ll be able to concisely formulate confusing or undefined thoughts into exact words. Vague thoughts that you considered in your head will either prove to be valid and gain strength throughout the process of formalizing them into words, or quickly fall apart as flawed ideas once you see them on the screen.
This habit will make you not only a better communicator, but also a better, clearer thinker.
2. Blogging can improve your technical skills
One of the most successful learning technique I know is to try to teach what you’re currently learning yourself to other people.
3. Blogging can provide you with a repository for your knowledge
Some people like to use personal wikis for this purpose, but blogging can be an excellent way to keep track of information you intend to retrieve at a later stage.