The Dragon Binding Lock is so powerful precisely because it is directly related to the ninety-nine Dragon Balls within the dragon's body. Once ensnared, the energy outside the body cannot enter—all of it will be absorbed by the Chain Dragon. Although one can struggle, the sturdiness of the Chain Dragon, along with the support of the ninety-nine Dragon Balls, definitely isn't something any opponent of the same level can escape from!
In the absence of energy replenishment, once the energy inside the body is exhausted, it's pretty much a death sentence. Without the support of energy, even the largest dragon is no more than meat on the chopping board, ready for the taking.
Of course, the Dragon Binding Lock isn't invincible. Although once someone is ensnared, they're in a bad spot, but that's if they can be caught in the first place. If the opponent were Xin Yun, Yi Luo Xiang, or Yan Qingying, it would be nearly impossible to catch them.
