For papers, this division of labor is a little unusual, but not outside the realm of normal practice. First author position is normally given to the person who is the lead on the project, not necessarily the person who actually contributed the most words to the manuscript. PIs often have a lot of experience with writing papers -- in particular, framing the narrative of a particular study so that the most innovative/interesting features of the work are highlighted, and so that the paper gets noticed by the intended audience. Also, sometimes another author (e.g., second author) will take the lead in writing up work that, for example, another student was close to finishing but did not complete before graduation.
Not using any of your words is a more extreme position, and is definitely on the "micromanaging" end of the spectrum, but I don't think it's unheard of.
As far as blog posts go, though, while I don't have a lot of personal experience in this area, a "ghost-writing" arrangement feels strange to me. I would not feel comfortable listing a blog post I didn't write on my CV, for instance. I think the difference is that generally, in blogging -- in contrast to journal articles -- the text is the whole point.
I can maybe see this happening if the blog post was a description of a side project I performed and for which I made figures or illustrations -- but even then I'd expect joint credit in the byline, not sole credit. I guess it's possible there are different conventions in your field, though.
One larger point that concerns me is that instead of really teaching you to write for a research audience, your advisor is just taking the wheel. That's an important skill to learn in grad school in and of itself. If your advisor isn't willing to take the time to teach you this skill, I would try to find an additional mentor who can.