User blog comment:ImperiexSeed/The oldest being, archangel or leviathan?/@comment-108.232.93.249-20140923072003/@comment-5619706-20140923112304

It's called plot armor. The same reason Death was also bound by the Winchesters and why Eve, a being capable of depowering a Seraph powered by Heaven's Weapons and 10, 000 souls, was killed in just one confrontation.

And you're wrong, Sam wasn't there.