uhhh... I have.. the pins make the exercise MUCH harder, ever heard of starting strength? You're a noob, go read supertraining. That slight bounce causes a reflexo-supramaximal contraction due to the plyometric nature of the exercise. Any time you experience a large amount of tension in such a brief amount of time, explosive/reactive strenth & thus RFD/starting strength improve, more significant beneficial changes to fasciae & tendon occur, along with higher activation of alpha gamma motoneurons occurs.
Think of this style of pin squatting as a depth jump with a barbell on your back, that's how the pins work. I've done depth jumps from 30" boxes with 135 lb bars on my back and ill tell you one thing, it's not fun, so that's why this method was created ~30 years ago in soviet compounds, to target this issue.
??? Can you dunk? Oh ok, didn't think so bushidobroad.