Why does ender treat bean like he was treated by graff? Will this help bean to be a better soldier or leader

Ender understands that to push Bean to his limits, he must isolate him in the same way he was isolated by Graff. Isolation invokes the knowledge that you're alone, and that you must become as strong as possible. I don't know if this type of treatment makes a better soldier, but it will make a tougher soldier. Leadership is not for the faint of heart.