The image below shows my old pair of Garmont Syner-G tele boots in both a Bishop binding and a fixed toe box tele binding (22 Designs Hammerhead). The plastic bellows of these boots have compressed and taken a "set" as they have been used over time. When the boots are flat on the ground the toes curl up. Know to us and Santa as the "elf toe effect". When boots like this are placed into a tele binding like the one on the right, it causes the heel to lift off the back of the ski. When the boot is placed in a Bishop 2.0 binding, the toe bail allows the boot to flex up at the toe and keeps the heel on the ski.
In both of these scenarios, the boot does not engage the springs until the heel is at about a 10-15 degree angle, BUT in the case of the fixed toe box binding on the right, the heel is being actively pushed up until you hit that 15 degrees. This has been called "rocker launch". With the Bishop 2.0, you eliminate the Rocker Launch and get a nice neutral feeling until the springs engage. you go from no force to a smooth progressive flex, vs an upward force, through neutral, then to the springs engaging.
With a Power Block and the Main Pin in position 3 takes up this neutral zone in most boots, and gives you immediate engagement as you lift the heel.