Off course that is becuase it has been portrayed as a fire without the explanation of the complexity of the event.
We first had an impact with the damage to critical elements of support. We then had a group of jet fuel assisted fires working in multiple areas with plenty of burnable materials in place to burn. The fuel was largely burned and blasted off in seconds but the ignition was critical. The structual collapse wes turned from incidental to the climax of the fire into catastrophic due to the incredible height of the building creating a huge kenetic stored energy source due to the height of the building.
The collapse of the burning floors thus unleashed the entire weight of the upper fourth of the mass of the building from a great height and the more it destroyed below it the greater the collapsing mass became.
I will try to look up a good forensic analysis of the event for you to examine, but I put that stuff away years ago.
It was a very unusual event but would happen in a similar manner to other structures of this height and construction.
and your answer for Bldg #7 is?