Ooookay.

（ don't mind him, he's just putting his hands on cas' shoulders and gently steering him away from the stage like the doddering uncle at a family dinner that's said something spectacularly Bad with a capital b. ）

Don't mind him, kids, he's just into gritty realism.

（ castiel please there are toddlers here!! once they're far enough away from the pack of youths, sam lets him go. ）

I think it's more about the symbolism inherent in a baptism by blood to rid themselves of the villain's influence. Personally.