On Writing
How is it that we look at a bunch of squiggles and start hearing noises in our heads?! Or, am I assuming how you think—is not all reading is "verbal"?! Writing is a peculiar thing that anybody reading this probably takes for granted. How very "meta"—you are reading about reading!
That which we call "writing" is a general skill of recognizing and interpretting symbols presented graphically—that is a spatial (most often 2D) arrangement of some stuff into a discernable form. This can be in brush strokes, on a digital display, with braille dots...
One may also speak of writing as in writing music, doing a particular type of shot with camera/film, or in the case of the Christian tradition—Iconography. How writing is done can vary in quality—hopefully this web page is aesthetically pleasing enough 😁
Linguists on Writing
A point of dogma for many linguists is that writing isn't Language (or some variant of this point). This point resonates with many people because of the social justice implications of holding this view—evidently, not all people groups have writing systems. So as to not say that certain people groups have "more developed" language than others, it is necessary to either (1) assert that writing isn't language or (2) redefine "writing" in such a way that using a writing system is nothing special.
Here, we return to a more general field of study than "linguistics proper" called semiology...
Literate forever
Writing fundamentally changes how people approach communication. Even if you never touch another book in your life, the idea of "recording speech" is forever in your head. You cannot escape the idea of "alphabetical order".
To neglect writing in the study of "language" is like trying to study the form of bicycles while ignoring the anatomy of human riders and the condition of local roads.