That is because that statement is both not useful in the context (you're there to pick it apart) and reflects pretty badly on your understanding, clearly the text has some depth, even if not consciously included, to be analysed. If your conclusion was "rubbish" when you're meant to be making a point about subtext, you're failing, its pretty simple.
People include subtlety in their art even if they don't intend it. Things can not be fantastic but still reflect society, the author, your own experience, which is the point of literature analysis.