I am sure there were cavemen who held out against fire and wheels as well. Modern mediation is a new way of handling disputes. Traditional mediation, which has existed slightly less long than disputes, was based on a sense of community and belonging. Usually, the village elder would be called upon to resolve the dispute. As people left communities with strong links traditional mediation ceased to have a role in urban centres.
The last few decades have seen the rise of modern mediation. Mediation is still in its infancy and like everything it takes time to get the message out.