1. Your Experience is Unique
Your past is not parallel to anyone else's. Things that happened as a kid, choices you made, your parents made, landed you to where you are today. For example: My experience is unique because I wasn't really exposed to computers growing up. I grew up in a very rural area, and didn't discover programming as an option until a class in college I admittedly signed up for as a misunderstanding. I HAD NO IDEA what I was doing and quite frankly had no business doing it. Do you think there's others coming into this field that are also stumbling their way through this? Yup.
2. Help Shed Perspective for Others
When I was a junior developer, I didn't feel like I had enough pull or knowledge to share with the world. But what I realized when I gained some experience is that there were people behind me just trying to accomplish what I did - getting their first job, or landing an internship, or attending a career fair. All those things are valid experiences that someone attending their first milestone will surely look up advice for.
3. Make a Name for Yourself
As you blog, you'll begin showing up in Google searches from people looking to learn more on what you wrote about. You have already marked yourself as knowledgeable on that topic! Now imagine this, when a recruiter searches for you, they find your blog where you share about ALL the things you know! How impressive does that look?
4. A Coding Trail
Have you ever had to do some tricky code that you have to look up every single time you use it? I know I have. The best decision I made was to blog about it, so the next time I needed to look it up, I knew right where to look.
The other dynamic of this is that you have a trail of how far you've come. Sure it's embarrassing to find your old code out there.. but everyone grows and improves. It can also be a fun exercise to look back at some old posts and improve on them.