Oh yes, it definitely can. On the one hand, it can be easier to work with someone else's idea - you have it all ready. On the other, you practically have to get inside the other person's head to get it exactly the way they want it.
Exactly. I can't just make it something really cool like a Dragon riding a meteor away from an explosion, because it means nothing! It has to be something that fits him, not just cool. That and I can't draw anything that well, except rocks I guess, so unless his cutiemark is Tom I am out of luck in creating it.