Why were the Torah and the Gospel revealed all at once, and not gradually like the Holy Qur’an?

The Torah was revealed all at once after the destruction of Pharaoh, at a time when the people of Moses could read and write. In contrast, the Quran was revealed gradually to an unlettered nation to address the challenges posed by the polytheists, to strengthen the heart of the Prophet (peace be upon him), and to facilitate its memorization and understanding incrementally.