That looks more of like a brainstorming overview for basic mechanics than something comparable to a game design doc

you may have confused with mere brainstorm flowcharts but noun-verb diagrams are also for what could interact with what instead of going over multiple pages like you usually would in a GDD, and think about more how the player is using the game mechanics throughout the game (use of game systems through game mechanics), its a more visual approach than of GDD ideally you would start from elaborating all the game mechanics to properly elaborate the rest to be balanced to them

story/backstory, the art style

those could be written separatedly from the noun-verb diagram since yes its not a part of the process of going over "what interacts with what" and still get the benefit of having a noun-verb diagram specificity and more organized on the artistic side of the game

helpful screenshots of other stuff to compare to and keep people on the same page

correct me if im wrong but i dont think many people are relying on GDD for that? i could be wrong though, this seems it could be a separate part of playtesting and version management documentation