Why did Mercedes agree to lighten their load before leaving for Dawson The Call of the Wild?

Mercedes agreed to lighten their load before leaving for Dawson in "The Call of the Wild" because the heavy burden was proving too strenuous for the dogs and the team. She was persuaded by John Thornton and others who recognized that reducing the weight would improve the dogs' performance and chances of survival on the challenging journey. This decision ultimately reflected her lack of experience and understanding of the harsh realities of the Yukon wilderness.