This question headlines an article by Sean O’Hagan in the Guardian.
O’Hagan writes: 

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.
….
As a writer, Szarkowski was innovative; as a curator, he was revolutionary. In 1967, during the so-called Summer of Love, he curated a show called New Documents at Moma. It featured the work of three relatively unknown photographers: Diane Arbus, Lee Friedlander and Gary Winogrand.
… 
At Moma, Szarkowski also hosted challenging shows by pioneering European photographers like Lartigue, Brassai and Cartier-Bresson.
…
@guardian.co.uk

O’Hagan of course mentiones the famous controversy in regard to the first William Eggleston exhibition at the MOMA (the New York Times declared it the worst show of the year), but those who follow my writings know that my angle is not on Western photography.

And in this case I just would like to remind of the fact that John Szarkovski also curated the seminal exhibition “New Japanese Photography” in 1974. In my opinion the qualitity of the selected artists/works - among others Ken Domon, Yasuhiro Ishimoto, Shomei Tomatsu, Kikuji Kawada, Hiromi Tsuchida, Masahisa Fukase, Ikko Narahara, Eikoh Hosoe and Daido Moriyama - and the essays by Szarkowski and his co-curator Shôji Yamagishi set the benchmark for all Western exhibitions and writings on Japanese photography to follow. 

See more on Szarkovski and his exhibition “New Japanese Photography” in a post from 2007 at my main blog: John Szarkowski (1925-2007) and Japanese Photography

Masahisa Fukase: Yoko Fukase at the MoMA opening of “New Japanese Photography”, 1974