User blog comment:Xilinoc/Ch. 573 (Let Unohana return plz)/@comment-24113610-20140319231859/@comment-9050606-20140320063653

He's got to have some limit to his ability. Otherwise, he could have just thought "All the shinigami are dead" a long time ago and everything now would be irrelevant.

Although there have certainly been characters before who had incredibly overpowered abilities but didn't even try to use them to their full potential.