There is a tremendous difference between a 1 1/2" thick 2x4 under the heels, which provides load on 2 places against the foot, and a weightlifting shoe with a solid wedge sole 5/8" thick. The 2x4 allows a lifter with tight hamstrings to not stretch them out, while the shoe provides a little better knee position for use of the quads at the bottom as well as a stable interface between the foot and the ground.