I think it comes down to writing blogs because you want to, not for career growth. It can be good for exposure but not if treated as a chore. The quality won't be there if the person is not that into it.
I think the best way to grow your career is to grow yourself. That could be through study, experience at a job, side projects, or blogging. Blogging gives a developer practice in written communication, which is a large part of any job. Having the ability to take something complex and explain it in writing is not always the easiest task. It also helps reinforce your own knowledge by having to explain it to others. It takes time and isn't a guaranteed win though.
It can lead to "exposure", which can lead to opportunities, which can lead to jobs. There are posters on this site that I only knew through their posts, have seen them show up as guests on podcasts, have seen them become podcasters themselves, or have seen them speak at conferences. I think that will benefit them greatly if they go job hunting.
That's a great point that blogging/writing improves soft skills that will directly translate over to job interviews (or even just making connections).
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