Why would you be involved in their loans at all, if you're the seller of the house? How would you know what they were putting as down payments or what their incomes were?
I was given the information to help base my decision on which offer to accept. The idea is that the better qualified buyer has a better chance of actually closing. I thought it was a little strange as well. Each of my offers came with details about their financing, and in a few cases, the buyer's income information.