This is not the case. It strengthens the stock pack and total wheel travel is greater than the replacement spring pack.
Spring rates are almost identical between the two.
The advantage of the factory leaf is the use of rubber bushings, which are quieter than the Poly bushings. I do recommend the new spring pack for older vehicles where the stock springs are excessively fatigued or damaged. In either case load capacity and stability are increased. A moderate lift block or extended shackle can be used to gain more lift.