The phrase "answered the purpose" typically implies that something was successful or accomplished its intended goal. Antonyms for this phrase could include phrases like "missed the mark," "fell short," or "failed to achieve its aim." These phrases suggest that the intended purpose was not met or that the result was unsatisfactory. Other antonyms might include expressions like "overshot the mark," "overachieved," or "exceeded expectations." These phrases would suggest that the outcome was successful, but perhaps went beyond what was necessary or intended. Ultimately, the antonym for "answered the purpose" will depend on the context and intended meaning of the phrase.