I think we agree on the basic point but my added qualifier really arises from my experience as a lawyer, where I have seen quite a few people over the years who

I think we agree on the basic point but my added qualifier really arises from my experience as a lawyer, where I have seen quite a few people over the years who never quite attain the ability to write really well because of intellectual limitations, though they can write at some level and though writing no doubts helps them develop the cognitive abilities they do have.