This is about WTC7, which was not hit by a jet, and did not come into contact with jet fuel. It's the only skyscraper ever to have collapsed from fire.
Also, as far as I'm aware, almost all skyscrapers with major fire damage are largely uncontrolled fires on one or two floors, rather than uncontrolled fires throughout the entire building.
Also: http://www.sfgate.com/bayarea/article/Tanker-fire-destroys-p... --that's a steel structure (overpass, not a skyscraper) being collapsed entirely due to an out-of-control fire (due to a crashed gasoline truck).
The jet fuel that hit the twin towers was mostly expelled in massive fireballs, with some of it draining into the towers.
I don't see a reason to believe WTC 7 was saturated in jet fuel. So WTC 7 was a paper & wood and fabric fire, right?