"If I pick Slumber in isolation and pretend that it only gets used in the most optimal and idealised setting, regardless of how little that setting resembles an actual game play environment, I can show you how unbalanced it is."
A Balor can choke to death on a potato too. Lets ban potatoes.
But think of the implications! Without potatoes the southern Andoran harvest would be ruined, Cheliax would collapse under export ban and Ustalav would rise as the supreme super power with its abundant supply of alternate starches!