Well, yes, you could be right. A well constructed door, made from decent timber could easily hold back a fire for 30 minutes. It might even have passed a BS 476 test years ago. But......because of the lack of intumescent strips around the door there will be leakage of hot gases and smoke around the door which will hasten its failure. It could not pass a modern test.
The chances of being trapped by a fire door are slim. The strips will not swell until a certain temperature is reached. At that point it will be too hot for life to be easily sustained. Until that point is reached the door should be easy enough to open.
The intumescent strips actually mean that the 25mm stops are not required. I have a BS document at work that details the behavioiur of a door when it is subjected to fire and what happens to its shape and integrity. It also shows how the number and position of the hinges can affect the movement of the door. This movement under the stress of heat and flame is what dictates the usefullness of the door in these conditions. If it can bend it will pull away from the frame and let hot gases past. This will lead to premature failure. This is the main reason for the extra hinge.
We have to bear in mind that the door is as much for the protection of the firefighters as it is for the occupants of the premises. They will usually be gone by the time that the firefighters are going into the building and it is then that the integrity of the door is crucial. If it has not been installed in accordance with the BS it will fail before the pemitted time. That is not comfortable I can assure you. A lightweight door can last for a few minutes but the real thing is always a much better deal.
The BS has been around for a long time. It is harmonised with the European standards for fire doors and it produces doors that work under fire conditions. It is a stringent test but a very fair one. However, the standard of workmanship is absolutely crucial to the failure time. Leaving parts out that are in the manufactorer's instructions will invalidate the warranty and can lead to premature failure.
I was a fire officer but I am now a fire safety adviser, heading for my second retirement. Fire was and is a great part of my life. Fire resisting doors are probably one of the reasons that I am still here to talk about them, come to think of it! Scary!
Cheers.
SF