Are Medeas claims accurate that Jason would not have been considered a hero without her help?

Jason's success would have been virtually impossible without Medea's assistance. He won the Golden Fleece because of her mastery of the arcane (mysterious) arts. She killed her own brother in order to help Jason escape, and she was an integral part in jason's winning back his title in Iolcus. Thus, Jason would have to concede that his wife played a large part in the way his life turned out.