Outside of characters who have near godlike powers (besides Thor, the Hulk has almost killed him before), who was more productive than Banner? There is a reason he was made king, democracy ain't it m8. Also, before he retained Banners' brain power he literally was as stupid as a box of rocks. What made up for that was the fact that for him, anger = power. Every second, every bullet and rocket, every blow, his anger grows. That means limitless power.