User blog comment:ImperiexSeed/Supernatural Mysteries/@comment-1970092-20130107040526/@comment-3481504-20130210003920

As Crowley put it, "They'd smash us like peas." And again, by saying, "He's everybody's boss." Of course there were limits to his power, Hell, even Death has limits. Only God can do absolutely anything. Now, Castiel could've effectively ran the Universe if God remained MIA, and Death left him alone.