If one is shot out of a cannon, they are of utmost importance. If one is flying through the air with the greatest of ease, they are extremely helpful, especially in getting the practice needed. If one is gingerly walking the tight rope, high above the din down on earth, they are super comforting. Just about anything that combines altitude and precariousness makes safety nets advantageous.
For those attempting to make a big bang for God, or hoping to catch a tumbling, falling brother or sister, or for those just trying to get from here to there balancing on the so very little (at least in terms of life lived in this flesh), the covenantal safety net is, oh, so helpful. That web is weaved with the cords of grace and the knots of promise. Even with God's timely interjections in the daring-do of life in the Spirit, it's not one's skills that keeps the darers of godly deeds from making a big splat before God. It is the arms of grace.
Humans stray: good ones, godly ones, ones daring the grand sacrificial life that puts God first. Faith means keeping one's eyes fixed on Jesus: being human means being momentarily distracted, struck by curiosity and fascinated by interest, frightened by thunder, wind, and waves. Humans are interruptible, we get fatigued, and even find ourselves bored by what was thrilling such a short time ago. Humans on the high road, straight and narrow, balancing precariously against human instinct need safety nets.
Our safety net as a Christian is that God's love and forgiveness for us is not ours because we perform perfectly. We are not his because of our powers of concentration or our ability to get in the zone for a lifetime. Oh, we're dedicated to the high flying calling of God, but it's not our abilities that ensure that we can keep at that for a lifetime, rather than making one fantastic leap followed by a thud and the end of our efforts. We make it because of God's consistent and unfailing mercy and grace gets us to the end through repeated efforts.
Who doesn't need safety nets? Those who never leave the ground.