The allies used massive fire bombing on Dresden Industrial sites towards the end of WW2. Google it and you can see the photos of those buildings completely destroyed…yet the main steel supports remained. I watched the trade centers being built and the main supports were massive. Even with the outer skin and the concrete floors in complete collapse the main steel supports would not have collapsed.
Then, we come to number 7. No plane hit it and again it completely collapsed. No fire would bring those main steel supports down. Not possible.