I have written nearly thirty posts on Dev.to and supplied countless (constructive) comments on posts of others. On the whole, I have found the experience rewarding and the community appreciative and supportive, even when they disagree with me. Here are the three main reasons why I will continue to write and I suggest you try it yourself, if you have not yet done so. If you already write posts, perhaps you might want say why you do in the comments below.

Share understanding

I first set out writing posts on other platforms but often found the community to be, shall we say, disingenuous. My initial articles captured and discussed things that concerned me within the Software Development industry, in which I have built a career. I explained things I thought where going wrong and ways I thought the industry was changing, in my opinion, for the worse.
I had discussed such issues with my peers but was concerned I was just creating an echo chamber as the majority of my peers have a similar background to me, so of course share my concerns. I wanted to widen the debate to include others that might have a different opinion to me and hopefully be able to explain why, and by doing so reassure me that, my concerns are unfounded. That way I might improve my understanding and find ways to accept disagreeable changes.

Share knowledge

My educational background is in Computer Science and when I started it was the primary avenue into the industry. The industry has evolved, the range of skills has broadened and practices changed, largely for the better. I personally think the industry has far more opportunities for people from a far wider background. That said I do not agree there is no role for CS graduates in the industry, quite the opposite. I think building a team with an over dependence on developers with only bootcamp knowledge might be more cost effective (cheaper) but is foolhardy and limited.
Bootcamps do a very good job of showing budding developers how to use specific tools and technologies but seldom instruct why. Without an inquisitive mind or in a poor/inexperienced environment, the learning may cease shortly after completion of the bootcamp. In an industry that is continually changing, so must the knowledge of developers. I have learned far more since completing my CS degree than during my studies.
However, the knowledge I acquired through study has served me very well. The topics I studied were non-specific and foundational so have been applicable for far longer than I expect bootcamp learning might.
I therefor try to share some of the foundational knowledge I have, that is still applicable in modern development, but unlikely to be a taught in any bootcamp.

Share experiences

I should imagine most inquisitive developers continue learning after their studies and outside of work. Now days there are many avenues to learn beyond reading text books. There are podcasts, YouTube channels, on-line learning resources such Scrimba and Frontend Masters, and of course communities like Dev.to.
One of the best learning strategies I have found is to develop home projects as a way to confirming my knowledge and experimenting with new techniques, tools and technologies. This does require time (which is an expensive and rare commodity these days) and self discipline. Like many nascent music bands, it is often worth replicating what others have done and learn from them. To that ends, and to extract additional learning, I often document my home projects and share what I learned in the process.

In summation

The three reasons I have discussed above have a common theme: sharing. I hope to stimulate thought, discussion and feedback. I write not only as a one-way communication but as a dialogue and look forward to getting comments to my posts. Including this one.