In the times before the advent of electric torches, villagers forming an impromptu angry mob/ search party at night or intrepid explorers who wish to explore immediately an ancient temple they’ve just discovered suddenly realise that nobody present has the knowledge or means required to make the oil-soaked torches essential for their search- at short notice at least.
In a similar vein, ancient temples that have laid forgotten for centuries or even millennia are not actually equipped with oil-soaked torches hanging from the walls at regular intervals to aid the progress of intrepid foreign explorers seeking to loot the place far in the future.