So, I will throw my hat in this ring.
Fireproofing steel is a redundancy measure to cover your ass. It prevents or reduces the possibility of catastrophic failure. But it does not prevent steel from catching fire. That is stupid.(Steel doesn't catch fire. It can be a solid or a liquid. Any flames coming of molten steel is mostly impurities and/or air.)
Fireproofing protects structural steel from the SIDE EFFECTS of fire. HEAT!
Steel's tensile strength from a temperature rise of 0-1000deg F. is a 20% linear drop in a pull test.
Steel's tensile strength from a temperature rise of 1000-1450deg F is 70% linear drop in a pull test.
At 1450deg F Steel is glowing reddish/orange and has lost 90% of it tensile strength.
Heat Capacity
Now that being said the fire would have to be big or hot enough to heat steel faster then the steel can redistribute the heat. (A candle has a different heat capacity then a campfire. But both are relatively the same temp).
Try cooking a brisket with a candle(1000F to 1500F) and see if you would ever get a 190F internal temp throughout. Where the same brisket would be done in 1hr per lb. at 300F. from just the smoke from a fire.
So for all you "my grill, frying pan, etc. if fireproof." You're are correct. It will not catch on fire. But those same steel objects have lost a substantial ability to stay formed and/or support.
Would you want to be in the stands when a fire starts in the basement?
The fire alarm goes off. (or doesn't hope you have a redundancy measure in place)
The fire alarm goes off. But no one can hear it over game day noise. (hope you have a redundancy measure in place).
The fire alarm goes off, and we evacuate.
How long would it take to evacuate a stadium of 50,000 people?? What if the fire heats 3 or 4 of those H pile beams to 1450F while supporting 3000 people, 1 Mangino and the structure? Catastrophic failure.
Fireproofing would be overkill for many applications. But, Insurance companies like it and when you cant evacuate a building quickly due to large amount of occupants in building or shape of building(sky scraper). Then it's a no brainier.
"Fireproofing is stupid"- Scarecrow