there also tends to be an expectation that men (even those of us that are submissive) be dominant to some degree

This is an important point to make, for sure. Things like this will be greatly impacted by things such as cultural norms and expectations, so any statement that says “There are more D men than D women” needs to come with the caveat that there are likely biases in these observations, and that culture and upbringing have an impact, either deciding the ratio, or skewing it

I do tend to default thinking of men as Dominant, and that is in no small part due to culture, but I’ll add that this assumption is specifically outside of the kink community. In BDSM spaces specifically, I expect most men to be subs, but my own experiences could also be because I attract the guys who are looking for their “goth mommy dommy” 😅