The economic impact discussion to my reading is actually intended to establish standing, by showing a concrete and particularized harm to the plaintiffs. Generally, a well-formed complaint is trying to establish that there exists a 'case or controversy' which the court is able to redress, not necessarily to answer all questions of law, and generally not to make prophylactic arguments about your opponents' hypothetical defenses. The USPTO document is being used as an example of OpenAI admitting copyright infringement, which they seem to have been happy to do -- one hopes that they fully anticipated this lawsuit.