Because when you compare him to other dummy halves, he has the worst service of any of them. His biggest problem is that he doesn't know whether to run or pass it, and if he doesn't know, good luck being able to stick to a gameplan or control a game. Not to mention, Segeyaro's defence is incredibly mediocre. Penrith have always been suspect around the middle of the field and he's a leading cause of that.
Right now, the Broncos biggest problem is that they don't know whether to shit or wind their watch. They can't control games, they lose it constantly on the buzzer and Segeyaro doesn't fix any of that.
Brisbane have a better player in Kodi Nikorima. Let's back him, instead of looking to the past to fix our problems.