At C4SS: That'll Show 'Em

"So when your system for anticipating attacks upstream is virtually worthless, the 'last mile' becomes monumentally important: having people downstream capable of recognizing and thwarting the attempt, and with the freedom to use their own discretion in stopping it, when it is actually made.

"So what has the TSA done? It has further limited the autonomy and discretion of the passengers, and made it even less likely that they’ll be able to stop a future attempt at onboard terrorism."