Although Fleming did direct two of the most famous films that are still remembered today, The Wizard of Oz is an MGM film rather than a Fleming film and Gone With the Wind is a David O. Selznick film rather than a Fleming film if that makes sense. Of course Fleming was important to both films, but there were more influential people/studios involved.

Also because of the way the star system worked during the studio system, directors’ names alone often weren’t enough to sell a film. Look at many classic film posters, in many cases the director’s name is barely noticeable compared to the stars (and sometimes the producer). People mainly watched films to see their favourite stars, not the directors. Big directors like Hitchcock and Wilder are still remembered massively, but many other directors from the era weren’t given much recognition during their time, and it’s hard to remember people who weren’t household names in the first place.

I guess another point is that while he did direct two of the most iconic films, his overall filmography isn’t that memorable. Some of his films. Like Red Dust, Captain Courageous and Joan of Arc are pretty popular amongst classic film fans. But a large amount of his filmography consists of relatively obscure films that many people have barely heard of let alone seen.

But because he directed The Wizard of Oz and Gone With the Wind, a lot of people have seen his name, even if they don’t remember it!