I understand what you're saying, but my argument would be that fireworks and gas cans are not meant to be set off in narrow corridors or choke points, but that they should be used to manipulate combat areas to survivors' advantage. And people need to know that, if someone makes the mistake of setting off fireworks in a narrow corridor, then too bad, your entire team has to wait out the entire duration or take minor damage going through it.
At any rate, I still think survivors should be very precise as to when and where to set off fire aoes, as opposed to setting them off mindlessly. I mean, we are already somewhat conscious about how overpowered they can get, why not do it properly once and for all?