Though, of course, the GM would have to be comfortable with playing said chauvinistic settings realistically and not with the ham-fisted style of a 1950s "Girls can't be tough" and "Stay in the kitchen, girl" that seems to be more the product of a backlash against changing expectations and a need to reinforce gender norms. In most societies where certain gender norms are just expected, people just do what they do and say what they say. They don't need to say "You're a girl so we're not listening to you", they just don't listen.
But that aside....
The reasons why I'm not a fan of the average chauvinistic fantasy world is for a couple reasons. These include:
- The male protagonists get it easy. Unless they're playing homosexuals or disdained racial minorities, I'll have to struggle to do what my co-players get for free just because I chose to align my PC's gender to my own.
- Realism is normally judiciously applied to only certain scenarios. We don't need to worry about STDs or gangrene, but we do need to worry about men looking down to us.
- What may look like empowerment by letting us undermine and exceed chauvinistic expectations can actually be humiliating. It reminds us how easy it is for men to look down on us and how if we were not in a post-industrial society, the very men at this table would feel the same way about us.
- It also suggests that silencing women's voices (as sexist characters shouldn't be willing to listen to a woman's advice) and ignoring of individual women's strengths (when sexist commoners laugh at their years of training even though any trained fighter is bound to trounce them) is natural to the human species. After all, this isn't a true medieval world. Social structures would change to reflect that.
- Sometimes it's not even realistic. Sorcery and alchemy on the scale often found in most fantasy worlds should have as much of a social impact as technology. If my willpower can beat your sword arm, than why would society assume you could overwhelm me? Also a world with alchemy and relics could conceivably have a herbal form of birth control and family planning is a real door opener for women in a society.
- If there is no form of birth control, why aren't male character's alignments changed from Good to Neutral if they have sex with random women as they are conceivably damning dozens of women and babies to an unsupported and shameful existence for a quick roll in the hay? At the very least, it shouldn't be Lawful.
- It removes female role models as the average GM naturally (due to media influences) includes more male characters anyway and when you add to that chauvinistic biases, you're going to have an almost all-male cast. This is an isolating experience for many women which sends an unintended message that these sorts of adventures "aren't for them" and that they are somehow strange or different for wanting to be a part of them.
- It can also give chauvinistic players and GMs the chance to express their negative beliefs toward the very women at the table.
- Even if the players and GMs don't hold those beliefs, it can still leave the female player feeling targeted because she's having to hear these comments occurring around her a lot.
- Real world chauvinism is insidious. Smacking down a single commoner for giving you lip would normally lead to retaliation for violating social norms. If the social norm sides against the commoner, they shouldn't have given lip in the first place. Just look at Brienne from Game of Thrones. Random commoners don't mention what she should or shouldn't be doing because the class differences are way more important than gender norms and they have no right to counter her desires.
My gender has a long history of being told we're not good enough to be involved in any historic event -- whether political, scientific, religious or military focused. Those historic events that do revolve around classically female domains have either silence women or been ignored. Having to grapple with those very expectations in a fantasy world can be really hard as it means we can't even imagine a world where we matter despite our genitalia.
And that *can* really suck.
Naturally, your female players' mileage may vary but it is important to consider.