I would say that of all the benefits, the biggest benefits are the benefits it brings to the way you learn and communicate. Part of the reason is that it forces me to better understand and communicate what I know to others. It allows me to fill in my knowledge gaps, hear other points of view and find better ways to share information with others. Employers who review your work for a job who see your writing will see all of these traits, which is great because they are great qualities to see in a coder. Coders who can communicate well and learn well are much better in the long run.

I think it's better to focus on your own development through the writing than on the response and popularity of your writing because you have a lot less control over the latter. Having a famous blog is something that realistically cannot happen to everyone and the fame will usually die before your career. For yourself, it's better to see blogging more as an extension of how you build your career than to just become popular.

It also has the benefit of helping others by sharing information with them!