Digital bank transfer leaves a record. Bags of cash don’t.
People seeing the bags have memories though. The Clintons would have let the witnesses know to be quiet or be dead. Or more likely just thanked them and then expressed shock and sadness at all of their improbable suicides (like shooting yourself in the chest with a shotgun while swinging by the neck from a tree which was the latest WTF suicide of one of their associates) over the coming months.
Leaks regarding powerful people tend to come for reasons. That is, someone wanted this to get out. Who and why?