There's going to be sexist people in every community, but if you want me to be honest...
You're coming off as really antagonistic right now, like you want to bait people into a fight.
Now, do you go around asking players if they are dudes or assume we're all dudes? If the answer to that is no, then you understand the mindset of a lot of us more laidback, gaming-focused gamers. Personally, I don't care what someone's gender is unless it becomes relevant (like we became friends or something, in a random game where we only play once together there's almost no way it's going to come up).
If you want to make a big deal about gender, there's movements and you can be active in the community to raise awareness I suppose. But when it comes to the actual gaming, nobody is going to make a deal out of it unless you do. Not a lot of us care in the first place.