Poll: Butter or margarine in a crawfish boil

I need to know ya'lls take on this.. I will break someone's arm if they attempt to throw sticks of margarine in my boil, it doesn't mix with the water, leaves a nasty slime all over the bugs, and doesn't help peel anything IMO (crawfish are NOT hard to peel till late June/July), but I have friends that swear by it, and refuse to listen to me. Am I just totally wrong? are they doing it wrong?