I don't think that's a claim you can validly make. Perception of how hard it is to get things onto a plane can prevent attacks. And unless you screen everyone's minds, you can't know that that's not the case. I'm not saying the balance is right.
https://www.huffingtonpost.com/2015/06/01/tsa-fails-95-perce...
There is a term for what you described, security theater. I'm not saying it's worthless, but it's only not worthless because terrorists might believe it's not.