If Mary, the Mother of Jesus, was sinless, as the Catholic faith declares, why then ...?

God's word let's us know how Jesus felt about exalting Mary; Luke 11:27-28, "...a certain woman...lifted up her voice and said unto him, Blessed is the womb that bare thee, and the paps which thou hast sucked." Jesus answerered her, "Yea RATHER, blessed are they that hear the word of God, and keep it."