I'm not Synapsin, and I'd very much like to hear his opinion on this, but if I can take a stab at it, the following may be potential reasons/explanations (note: I am not in any way saying that I personally agree with any of the following, only that they may be potential issues and/or things that other people think relevant to the topic):
-Men vs Women as supplement buyers. The majority of supplement users/buyers tend to be males, which means that they wouldn't be using a women's libido supplement for personal use. This trend still seems to hold true among educated supplement users and forum members; most of us here are guys, I think (it's 2017, who knows who identifies as what).
-Differences the relationship between libido and sexual function between men and women. Of course, while libido and sexual function and performance are related, they aren't inherently the same thing; one can have libido and not proper sexual function (ex: can't get it up), or proper sexual function but no real libido (or desire to have sex). Of course, libido, or becoming excited/aroused, can often improve sexual performance. Often times, men will think that something that improves libido will make them harder and/or last longer (be better in bed), so they look for a "libido supplement" when they actually want something that will improve sexual function (which aren't exactly always the same thing). As a male, if you can't get it up, or keep it up, sex becomes difficult, if not impossible, so guys will want to remedy this problem for sure. On the other hand, women don't have to "get it up" to have sex, hence the common stereotype you see/hear about women "just going along with it for their husband" or "faking it." Perhaps a man is more likely to be concerned with and conscious of his sexual performance than a woman is, which could lead more men to seek some sort of "enhancement," with a common thought process of increasing libido = better performance. Of course, that's not to say that women don't also want to be better in bed, or enjoy it more, but, in popular culture at least, sexual encounters usually end prematurely because of the man.
There are supplements that have research showing that they can improve female libido and/or sexual function:
Ashwagandha:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609357/
Maca:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4411442/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2928177/
Potentially Tribulus:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4045980/
Fenugreek:
https://www.ncbi.nlm.nih.gov/pubmed/25914334
Sorry for hijacking your thread Synapsin. Hopefully I made a little bit of sense though. I definitely look forward to hearing your input and opinion on this topic!