See thread entitled, "Reasons a Wife May Refuse Marriage Debt" for a concrete example of the practically of having an anonymous option on the men's/women's forum. These threads turn into men vs women disputes instead of receiving good advice from people who may be going through, or have been through the same thing; from the perspective of a person of your sex who understands. :cheers:
In this case, I think seeking such advice from your gender only is too likely to just be putting yourself in an echo chamber. Discerning adults can take multiple POV into consideration and acknowledge that there are biases on all sides.
However, there are other topics where I could see wishing to discuss something with those of your own gender would be most beneficial. Female health concerns, perhaps.
I think the idea of a gender-specific, anonymous forum is too prone to abuse, though. Considering most people are almost entirely anonymous to begin with, the isolated need for another option should be taken up with the moderator... who can post the question on your behalf, perhaps.