So, the general idea was that everyone is fumbling around in the dark, so any information they have about the world is limited and possibly just straight-up wrong (hence the "It might be true" line in the SENSE entry).
Lighting a fire gives you a way to actually see your surroundings, but carries a tremendous risk since it also reveals your position. The matches were just there so that players have limited means of creating fire
SENSE isn't meant to require a roll, the GM just tells you something about the world that may or may not be true. Lighting a fire is a way bypass that uncertainty, but at a cost.
I hope that helps.