Flakes are common on granite routes. You can usually put cams or nuts behind them, though. In this case, the flake is very loose and the gap between the flake and the rock behind it is very wide. If he did manage to place any large active pro behind it, it might pry the whole flake off in a fall. This would probably kill him, his belayer, and any people on the ground below. This is why it wasn't climbed by anyone until he invented this device, which won't pry the flake off the wall.

One of the most famous granite flakes is the Texas Flake on the Nose route on El Capitan. The gap is so wide that you can't place any protection and must chimney up the 5.9 pitch with no pro.