Did you know that there’s a term for a figure of speech that means the opposite of hyperbole? I didn’t, but it’s derived from the Greek word meaning “simple.”
“A deliberate understatement for effect. For example, a good idea may be described as ‘not half bad,’ or a difficult task considered ‘no small feat.’ Litotes is found frequently in Old English poetry.”
That Dr Seuss fellow didn’t lack an imagination.