First, myopia is NOT a pathological process or a disease process. For the vast majority there is no tissue damage, no inflammation, or any other malfunctioning tissues. The eye can change its length through a feedback system that is based on how the eye is used.

When you do lots of near work, the eye has to focus up close, and this causes the eye to have to constrict the ciliary muscle. When we look at distance, this muscle is relaxed and the eye does not have to expend effort to focus. Since constantly firing the ciliary muscle to see up close is tiring, the eye adapts: it changes shape and lengthens to reduce the strain of constantly focusing up close. This system is native to the eye itself and requires no direction from the brain. If you cut the optic nerve, the eye will still change shape depending on the task it is performing.

So the myopia shift seen in people who do lots of near work: students (especially graduate and doctorate), those who read a lot and those who are rarely outdoors allowing their accommodation to relax will see this shift most. So you are correct, that it doesn’t DIRECTLY cause the eye to grow longer, but the eye does intentionally lengthen when exposed to constant near work.