User blog comment:Fusedtwilight/Season 9 plot/@comment-24169020-20130517022713/@comment-1509826-20130517224051

That doesn't explain why he's so powerful though, unless being king of hell literally makes you more powerful. Azazel, Lilith, Alastair, Samhain and Abaddon are all ancient, there thousands of years old atleast. Crowley is somewhere bellow them but he is only a few hundred. My best guess its a accumative thing.