User blog comment:Fusedtwilight/Season 9 plot/@comment-24169020-20130517022713/@comment-2020973-20130517222457

I think it's partly age. Lilith, Alistair and Abbadon are old and super powerful. I think Crowly got the job because he was very influential and well liked by other demons. Abbadon was about to kill Crowly and take his job, showing disgust someone like him was the king.