Maybe it is the effects of “Jesus and me” Protestantism on the lives of individual Catholics but Catholics have gotten away from the idea of shared suffering and shared redemption. Catholics seem to forget that we are one body and that our salvation is not achieved in a vaccume, nor is our damnation.
Our suffering can be redemptive for ourselves and other members of Christ’s body. Likewise, any grace we merit by our perseverance and endurance to faithfullness in the face temptation can be applied to the entirety of the Christ’s Body. As the preeminent and sinless member of Christ’s body chosen to hold God in her womb, Mary has earned infinitely more grace for her son’s body than any of us. As the one who God chose to bring Christ’s body into the world, as the Mother of the Savior, Mary naturally mediates the application of all grace earned by her and all other members of Christ’s body to her Son’s Body, which is the Church.
As pointed out in the excellent quotes posted by JM3, Jesus justified us, but he grants favors (graces) through his Mother Mary as the preeminent member of His Body. I don’t know why Catholics have a problem with this.