Perhaps it's as simple as it is very difficult to be well-read in any literary genre these days, but most especially in those genres that have a multilingual authorial and reader pool. In the 21st century, English may still very well be the preeminent language of discourse, but there are some outstanding women writers writing in languages such as Spanish, French, German, Japanese, or Finnish, just to name a few that come to mind. From older writers such as the Argentine Angélica Gorodischer, the Finnish writers Leena Krohn and Johanna Sinisalo, or Élisabeth Vonarburg (French/Quebecois) to younger writers such as Juli Zeh (Germany) or Yoko Ogawa and Banana Yoshimoto (Japan), these are just the most prominent female SF writers who do not write fiction in English. Lately, there have been dozens, if not hundreds, of writers, men and women alike, who hail from non-Anglophone countries yet whose stories have been composed in English.
It is easy to wag my finger and say that lists such as the one linked to above should be more "diverse," but the reality is that it is so very difficult for even those readers such as myself who manage to read hundreds of recent releases each year to be kept fully abreast of what is available in any given literary field. I have a list of over 160 works published for the first time this year in either US or international editions (in those cases, first overall publication) from which I have reviewed and/or read over 90% of the listed titles. Recently, major literary and newspaper publications have begun publishing their Best of Year lists and at best I have read around 1/4 to 1/3 of the titles listed (a great many of these being books that will make my Best of 2014 lists later this month). At first, I felt almost ecstatic seeing that so many books that I enjoyed also made others' lists. Then it dawned on me that there are so many areas in which I have not read as much and that there are likely hundreds, if not thousands, of recent releases in a multitude of languages, not just the English-centric lists that dominate discussion these days, that may be equal to or superior to the titles that will grace my lists.
This is a sobering realization, that no matter how much one tries to be diverse in her reading, no matter how well-read he might be, there are just so many limitations that cripple our ability to identify and to praise exemplary writers. But maybe that's precisely the point of creating such lists. Maybe we list makers, while in the act of contemplating what we view to be exemplars of modern literature, should consider what we are most certainly missing and to have a humbleness about us that allows us to strive to shrink, even if it's just a bucket scooped out of the oceans, that vast body of unknown and unrecognized works just a teeny-tiny bit. Perhaps it is in the identifying of what we do not know, of what limits and confines us, that we are able to understand ourselves and each other (including those now-dead writers and their thoughts and concerns) just a bit more.