I hope you're actually an American who doesn't like the NFL so you can tell me how well the analogy follows.
The conversational equivalent using the NFL example would go something like this:
"Why are there no Americans at my favorite chess forum?"
"Americans like the NFL. They're just more into brute force and camaraderie, especially American men. Chess can't really appeal to them. I mean, back in the Neolithic, a modern day chess grandmaster, if he managed to not burn in the sun and see an angry cougar 15 meters away, would probably have died. American men are just closer to their nature. I have this cousin who's American, I have attempted for years to get him to play chess and no dice. Not during the season, anyway."
"I mean sure but there are American chess clubs? Some Americans like chess? Surely the cougar thing is not relevant to my original scope?"
Now, you're a chess loving American. You're not at the first poster's forum because you can't be on all the forums in the world, and it's true love of chess is not exactly common in the US. However, how would you feel reading the description of how apparently literally everyone else in America loves the NFL? Would you feel proud to be American? Would you feel like the poster who made the NFL comment is likely to be an American man? Would you be more, or less likely to read his further arguments on different or related topics, for example, his opinion on American politics?
While I'm sure that there are plenty of women who don't mind those arguments being made, and I think to an extent this forum would select for those women anyway, it remains an argument that is, in essence, 1) prone to being misinterpreted and 2) a little blind to your audience. (the subject is chess - you are talking to a chess fan - for all you know the chess fan also loves the NFL)
And those arguments are less effective than other arguments, for example, the kinds that 1) don't make assumptions of their audience and 2) are closely related to the topic.
(I realise this digression itself is totally off-topic and I'm sorry. I'm not interested in monologuing or haranguing the poster or anything. I hope it, and the little NFL parable, showed you and the people who usually make that argument without thinking about who reads it, a slightly different side, and that you may consider it if in the future you should have longer debates on relevant subjects with people whose opinion and background you don't know a priori. And thank you to anyone who read it.)