Earlier quoted context omitted.
there's no such thing as grammar I'm not sure what you mean by this. Certainly adjectives are a thing, and if I learn a new adjective, "anguilliform" for example, I have never heard that in context, but I know exactly how to use it. That is grammar, right?
I'm being hyperbolic, but what I'm suggesting is that grammar is a convenient fiction. The part where you speak of "how to use it" points to the break down in your thinking. (Side note: look into the difference between prescriptive and descriptive linguistics for a sense of where I'm coming from on that point.) So, you learn a new adjective. Surely you can use it like any other adjective, right? Sure. But someone can…
I don't think that's right either. It's not fiction, it's definitely something real.