To know every detail of the oil trade… this was John D. Rockefeller's ideal of doing business. It seemed to be an intellectual necessity for him to be able to direct the course of any particular gallon of oil from the moment it gushed from the earth until it went into the lamp of a housewife. There must be nothing — nothing in his great machine he did not know to be working right. It was to complete this ideal…that he undertook to organize the oil markets of the world... Mr. Rockefeller was driven to this new task of organization…by that thing so abhorrent to his mind — competition. If, as he claimed, the oil business belonged to him…it followed as a corollary that the markets of the world belonged to him.
From Ida Tarbell, The History of Standard Oil Company, 1904
What commonly held concept was being challenged by Ida Tarbell in this excerpt?