The bounce has been around as long as the bench press. Its a cheat method to allow the athlete to get past the sticking point (usually the bottom 4" of the lift) with momentum to drive up weights that would be otherwise to heavy to handle. The cushion just takes some of the punishment out of the lift. Lately, the use of chains and/or bands provide progressive resistance, allowing for heavier loads at the top and lighter loads at the bottom. I don’t recommend the bounce method.