Due to the sustainability in sourcing raw materials and that using essential oils requires much larger volumes of oil in a candle. Essential oils also don't perform that of a fragrance oil - the scent is not strong and due to low flash point, when the candle is heated to dispurse the scent it is "burnt off" loosing its scenting ability. Essential oils are also costly which would be adding to cost per candle and forwarded to the customer. Fragrance oils are also much more user friendly.