Why don't 9/11 conspiracy theorists ever consider the possibility that US intelligence services might have acted incompetently with information preceding the attacks? Makes a hell of a lot more sense than being able to pull off an elaborate cover-up which ended up casting a shadow on the country for the following decade.

All I see is "the CIA/NSA/FBI/etc. would never screw up, therefore they were in on it". That's wrong on so many levels...