Conspiracy theorists seem to have a problem with Occam's Razor. When they can't find their keys, they first start thinking about dimensional transference rather than "Oops, I misplaced them." Official versions being what they are, there will always be some things that are covered up or lied about outright, or that they got wrong. As time goes on, we learn new things, so it's not like the story of 9/11 has finished being told. However, the important parts we have overwhelming proof for: four planes were hijacked by Al Qaeda militants, three were crashed into buildings, one crashed in Pennsylvania after a passenger revolt, and the Twin Towers collapsed because the fireproofing got blown out by the violence of the crash and the girders supporting the floors directly above the impact zone gave way once they became too soft from being heated by 2000 degree fires.