User blog comment:Staw-Hat Luffy/Why Kaido?/@comment-4374114-20130204184553/@comment-4374114-20130205210246

From the plan Law described in the latest chapter the whole intent of using Doflamingo is to help make breaking those defenses down, be it through prevent him from creating re-inforcements or even if they might fight each other. The only way they will get close to a Yonko is to first break down the crew.