A man appoints another man to be his shaliach to deliver either a divorce or a document that frees a slave... And then the man dies before the shaliach gets to the recipient(s), and there's no need to give the document - in contrast to one who owes money and is using a shaliach to deliver. Even after the man dies, the funds need to reach their designated recipient. So the Gemara attempts to apply the case to flesh out the details in a way that makes sense. Also, the case of the creditor, the debtor, and the creditor's creditor. And how timing can have impact on the transfer to pay back the loan. Can the debtor negotiate new terms? Why does this system work? Because it's already part of halakhah.