Basically, there are 4 reasons why I post articles on this website.
It makes you more open Blogging teaches you to share your knowledge and experiences with others. You become more open.
It helps you reaching goals Blogging lets others know more about you and your goals. If they like you're doing, they will react to your goals in a way that may help you achieving them more easily, using their network and knowledge. Also, you can put challenges in the open, so it's an extra reason to achieve them, because it will be bad for your image if you don't achieve your challenges.
It's Networking 2.0 See it as a way of networking. Instead of just talking to one person, you talk to all your subscribers, which is way more efficient.
It keeps your thoughts organized I use writing as a way to organize and pinpoint my thoughts. I think a lot and I have a habit of writing down important thoughts in notes anyway. I might as well post some of my thoughts online if it can be useful to others.