That historical context is further treated in an outstanding article by Alfred Tauber, who was professor of medicine and philosophy at Boston University School of Medicine.
In "The Two Faces of Medical Education: Flexner and Osler Revisited," Tauber contrasts the radically different views these two men held about the ethos of medicine and the proper approach to medical education. It is ironic that the victorious position would be the one pushed by Flexner who, as Murray Rothbard put it, was "an unemployed former owner of a prep school in Kentucky … sporting neither a medical degree nor any other advanced degree."
Tauber perfectly captures the aim of Flexner:
Flexner had another agenda than simply eliminating substandard institutions. The registration of medical schools with the Association of American Medical Colleges, the imposition of state licensing linked to such accreditation, the development of a model medical school at Johns Hopkins, and finally the effective use of philanthropic foundation support (e.g., Rockefeller, Carnegie) helped mould American medical standards closely to those advocated by Flexner. The 20th century doctor was to be an active and skeptical medical scientist.