Every one of these things applies about as well to adults, in my experience, at whatever age cutoff you use to define the word 'adult'.

Especially this one:

> They don't understand mathematics because their earlier instructors taught it as algorithms without context, the beautiful axiomatic nature of mathematics is never revealed.

And, in my experience, this is incomplete at best:

> They can't write because they don't read, which is where it is easiest to learn new words.

Learning new words is a small part of why reading is essential to writing. Most of it is learning new sentence and paragraph structures, which mirrors the new structures of thought required to compose those kinds of linguistic structures in the first place. Hemingway is an extreme example: You won't learn a lot of interesting new words reading his works, but you'll learn a lot about how to structure ideas.