> Many of the devs who struggle the most have some difficulty giving themselves credit for things they've done

Ain't that the truth. I've been an engineer for a decade, I built a career app, I blog about career management, and i definitely still struggle with this.

And you're right. It's not only about good writing. Writing a good resume is a specific skill. There are so many career specific factors that come into play (industry lingo/keywords, being able to quantify value etc), you can't just make it pretty.