Why, I cut the pelvic bone is: a) cooling, b) I can pull rearward from vitals to pooper and less chance of tainting, c) it is easier and quicker (for me) & d) the way I was taughtwhen i was 11. I have done them both ways, equally easy imo, but also imo for a first timer the pelvic bone cut or split makes it way easier and less chance of a mistake cut. Again just an idea, but definately no rule!