NTSB is motivated by fact, not by emotion. Here is a little background reasoning of where they are coming from during investigations like this:

"Another complicating factor in understanding and improving aviation safety is that accidents rarely have a single cause. Rather they are typically the result of a sequence of events involving several malfunctions and/or mistakes. Consider a situation in which an event initiates a sequence of other events that result in damage to an aircraft and/or injury. The same event might occur in another flight but not result in an accident or injury because something else was done to interrupt the sequence of events."---NASA

"We all know that accidents are rarely caused by a single cause -- rather, they are usually the result of a number of interdependent causes --" Jim Hall, NTSB, Chairman