Good Female Sci-Fi Writers are Hard To Find?

I just came across this via Pat's Fantasy Hotlist - Orion Books and Gollancz have just launched a really, really bad ad promoting a book by a female Science Fiction author, and one that seems to say that there aren't very many female science fiction authors out there, and that good ones are even rarer. From the back cover:

"Female SF writers are a rarity; good ones are even scarcer!"

and

"Good female SF writers are hard to fine - this is sure to be included on many SF award shortlists"

I find this to be really off base and frankly, pretty offensive to a number of female science fiction and fantasy authors out there. Off the top of my head, I can think of a number of absolutely fantastic science fiction authors who are also female: Karen Traviss, Nancy Kress, Elizabeth Moon, Ursula K. Leguin, Madeleine L'Engle, Elizabeth A. Lynn, Marion Zimmer Bradley, Octavia E. Butler, Naomi Novik, Julie E. Czerneda, Karin Lowachee, Anne McCaffrey, Liz Williams, Connie Willis, Mary Shelley and a lot more. There's a good list here: http://en.wikipedia.org/wiki/Women_science_fiction_authors

I don't doubt that this author that they're promoting is good - Jaine Fenn, with her upcoming book Principles of Angels. But to completely degrade a whole wealth of science fiction authors and their works is absolutely appalling - there's no justification for it at all.

http://fantasyhotlist.blogspot.com/2008/02/good-female-sf-writers-are-hard-to-find.html

The Science fiction field is largely unbalanced when it comes to gender. There's a lot of male science fiction authors out there, but overall, I think female authors have just as good of a time with it as men do. I don't know how they compare, but I suspect that there's a slightly more even split when it comes to awards and individual fame, once you adjust for time and cultural changes.

Of all the Science Fiction books that I'm looking forwards to this year, the most anticipated is Karen Traviss's book, Judge. I personally think that she's one of the best contemporary science fiction authors out there. Good science fiction authors aren't hard to find, and I think that nowadays? It's easier to find a woman author who can hold her own with any male author out there.