So the crux of it is the definition of wet. A couple definitions: “covered or soaked with a liquid such as water” or “Not yet dry or firm”. While you could maybe argue water is “not yet dry”, that also implies the expectation that it will at some point be which it won’t, because if it’s “dry” it’s not water anymore. Similarly water is not “covered or soaked in a liquid” as it is a liquid. It’s a subtle point but highlights a quirk of English. A liquid almost by definition can’t be “wet” unless it also has a dry state (E.G. paint).