Why was Ida tarbell critical of john d Rockefeller?

Ida Tarbell was critical of John D. Rockefeller because she believed he employed ruthless and unethical business practices to monopolize the oil industry. In her investigative series, "The History of the Standard Oil Company," she exposed tactics such as predatory pricing, secret deals, and aggressive competition to eliminate rivals. Tarbell's work highlighted the negative impact of such monopolistic behavior on consumers and small businesses, contributing to the growing public outcry against corporate power and leading to reforms in antitrust laws.