Hello,
I am by no means a part of those who host fcf, in fact, I'm pretty new here - at least as an active member - but I could share my personal observations on this topic. First of all, I agree with you that discrimination (and I mean discrimination of any kind, including racism - for there are people who will say black people can't be racist) can go both ways. That being said, I wonder if you're not, so to speak, a bit over-dramatizing the situation.
When it comes to those "I don't talk with men" in profile texts, I imagine two main reasons for their existence:
1. Those are written by "women" who in fact are guys pretending to be women. For them chatting with other guys would be pointless if their ultimate goal is to find cyber fight partners, because I imagine being a guy and fighting another guy in a manner that often has sexual elements might seem weird (unless you're a gay or a bi).
2. Those are written by real women who just have lost their patience speaking with creepy, overly insisting or boring men. Don't get me wrong, I really try not to generalize, and that's in fact why I am open to chat with men and also do mixed fighting - I have in this way discovered really interesting male partners even in my short career here. But, proportionally, compared to women, there are a lot of bores (maybe this is subjective and it's simply that our interest don't match...), for example, a lot of men here seem to secretly like to be dominated, which is nothing wrong in itself, but as a woman that tends to like "real men" (sorry for being such a cliché) for me this attitude is a big turn off, and I sense it pretty quickly just by chatting with them. If I win against a man, I want to feel that I won a real struggle, and not a fight against a moma's boy.
And in conclusion (as if I were writing an essay haha), I'd say, why bother with people who write this in their profiles at all, since - whether fcf team intervenes and makes them erase it or not, it won't change the simple fact that they won't chat with you anyway.
Take care!