Was John Szarkowski the most influential person in 20th-century photography?

The Guardian (July 20, 2010) - An insightful critic as well as a visionary curator, Szarkowski filled New York's Museum of Modern Art with the colour photography of William Eggleston, and championed the transgressive work of Diane Arbus and Lee Friedlander. Everyone who cares about photography is in his debt

It's three years to the month since John Szarkowski died: a good time to reappraise his role as a defining figure in photography, both in establishing it as an art form and in influencing the public's perception. Szarkowski was a good photographer, a great critic and an extraordinary curator. One could argue that he was the single most important force in American post-war photography. [...]