I've worked with many engineers who couldn't write, and it always came across in the aspects of the work mentioned in the thread — less ability to parse error messages, to describe things to others over email/Slack/comments, and most critically, to understand things that others wrote. Fundamentally, a huge amount of engineering is reading and writing. And I find those skills are very often linked.
Long story short, you will become an even greater engineer by drawing and writing out your ideas.
I don't think that applies here. Writing and reading are very basic skills that will help you in all aspects of your job as an engineer, and everyone should be as good as they can be at them.
On a (somewhat) less pedantic note I would add that “asserting” is a bit strong of a word to describe the statement I made. Perhaps you should be a bit more precise with your words. Writing more could help :).