All kinds of weightlifting variations I have traced back to competitive weight lifting, and powerlifting training methods. Read Supertraining by Mell Siff.
Weightlifting variations are used to prevent you from going stale, it prevents boredom, and it offers a new type of stimulation to the body.
Also, just to get this off my chest, I get upset when I hear people criticize lifters that they “cheated” because they bounced the weight, because, no.1, so what?!, and no.2 the people who criticize probably could not even UNRACK the weight themselves.