Table of contents
I'll start with something obvious here, but you don't need to be Stephen King to have a blog and write something; people will read what you have to say as long as it gives them something.
In this article, I won't discuss whether writing is good for your brain or something similar. Instead, I will focus on why it is important for your career as an engineer or at least how you can leverage it.
Your own image
Creating content about a topic, specifically blogging, is by far the easiest way to position yourself as an expert—or at least as an informed individual. It is okay if you want to be a speaker at an important conference, but that is not necessarily something you can control. Or maybe you want to create a YouTube channel, but you want to have a nice studio first, so you can't start it yet.
You can start a blog for free and create a very important picture of yourself on the topics you write about. You can use your articles as part of your resume or portfolio to demonstrate proficiency in the topics you are good at, scenarios you've faced before, and even showcase your communication skills.
Writing articles improves your image, regardless of whether you have your own platform or if you use something like dev.to or LinkedIn.
Your own knowledge
This aspect depends on how serious you want your article to be. I'm not talking about the tone; I'm referring to how trustworthy the content you create is.
For example, if you are writing about whether JavaScript is a compiled or interpreted language, you will have to read extensively and provide very solid arguments to support any side of the discussion. If you want to say that there isn't a solid answer to that discussion, you will still have to support that argument with facts.
You might have to reference Google's blog about the engine Google Chrome uses or a paper about it. The point is that writing content improves your own knowledge of the topic in question if you want to ensure that what you create has a solid foundation.
This doesn't mean you must be perfect; somebody can contradict — or try to contradict — your article in the comments, and that's okay, too. You can learn from that experience, correct your article if needed, or encourage the conversation.
Your own pocket
I'm not particularly interested in monetizing what I write (right now?); this is something I do for fun, but there are multiple ways to profit from this (directly or indirectly). For example, if you have more control over the page where your blog lives (like a WordPress site rather than Hashnode), you can have ads.
You can have a Patreon page for people to support what you do, you can create a YouTube channel or a podcast and use your articles as a base for the content on those platforms, and you can even create a course on Udemy to dive deeper into the topics you have covered on your blog.
Personal experience
I don't think everybody should have a blog or write articles; in my personal case, I do it because I like it. Whenever I write an article, I learn a lot and improve my own technical & communicative skills, but this may not be what you need.
Maybe you can leverage a YouTube channel more if that's a format you prefer, maybe a podcast is your passion, or maybe you want to create an Instagram account to post the content you like. Not everybody has the same needs and skills, so you don't need to feel bad if you want to create content but don't like to write. Find the format you like and have fun with it.