The problem of the jets on September 11 is the use of the jets themselves as weapons. Even without the jet fuel on board, the destruction would still have been

The problem of the jets on September 11 is the use of the jets themselves as weapons. Even without the jet fuel on board, the destruction would still have been substantial. Whether the Twin Towers would have fallen without the fuel is not really relevant. Most of the security is security theater. The primary improvements to security have not been people taking their shoes off or emptying water bottles. It was locking the cockpit doors and passengers knowing that they cannot rely on the hijacker wanting to survive. Other than that, making sure passengers are on board if their luggage is has meant no more Lockerbies. All the other stuff is pretty much a waste of time.