Unironically, an airliner plane would have a much bigger payload than most missiles. Way more mass, and filled to the brim with flammable fuel.
but jetfuel can't melt steel beams
A fuel-fed fire will blaze for a long time. When trapped in a building, that heat becomes an inferno. The fire can massively weaken the integrity of the supports in the building. With the crushing weight of the rest of the building, it's not hard to believe the building would collapse.
And every floor would have provided resistance all the way down. Which in turn would slow down. Everything is just not going to give out and crumble to the ground.
Unironically, an airliner plane would have a much bigger payload than most missiles. Way more mass, and filled to the brim with flammable fuel.
A fuel-fed fire will blaze for a long time. When trapped in a building, that heat becomes an inferno. The fire can massively weaken the integrity of the supports in the building. With the crushing weight of the rest of the building, it's not hard to believe the building would collapse.
So what weakened the bottom 80 floors?
The sheer weight and momentum of the top floors crashing down.
And every floor would have provided resistance all the way down. Which in turn would slow down. Everything is just not going to give out and crumble to the ground.