Sometimes they have legitimate reasons for doing so, but often they don't. People who don't closely monitor their lenders every step of the way and guard against trouble can easily end up stuck at the closing table with loans they can't afford or can't avoid. There's nothing that prevents them from writing a loan lock as they want it because all they do is stand behind and say we never guaranteed it. The consumer advocate part of me says this is a big consumer issue. For years, borrowers have swapped horror stories about last minute problems popping up before and during mortgage closings.
Sellers make unreasonable demands before they agree to sign anything.
Buyers have to borrow money from co-workers because they forgot about charges and have already spent their last pennies on down payments. Realtors and lenders get too busy, lose paperwork or otherwise run into trouble, delaying closings by a few crucial hours or days. But all too often, lender screw-ups, outright lying and arcane lending practices are at fault, according to borrowers and consumer advocates. Overzealous or undereducated brokers and loan originators promise loans they either can't or won't deliver. And because efforts to reform the mortgage process in a way that would prevent last minute problems have failed, loan shoppers keep getting ripped off every day.