When something is too obvious, smart people often reject it, overlook it and miss it. The too obvious seems "too stupid" and is discarded:
"If it was that obvious, they would never get away with it."
"If the perpetrators were smart enough to pull off something this devious and immense they would never be so sloppy to do something so obvious, blatant and 'in your face'"
Remember the "767" is depicted here as disappearing through solid floors of concrete, which extend in a flat plane to the other side of the Tower.
Since the "airplane" is tipped we are expected to believe "it" met solid cement at numerous points along the edge wherewith it intersected the Tower, yet did not slow down nor crash nor break apart, down even to the tip of the rudder on the tail fin.