It can't be disputed that history presents us with an impressive list of women who were strong and natural leaders, and I haven't suggested anything to the contrary. However, "upper-body strength" (I take it that you're implying this is the only physical advantage men have over women?) was a significant enough of an advantage to never qualify women as a practical military resource in times of war (as one example). Women like Joan of Arc aren't singled out by history because they were great or even passable combatants, they're singled out because of their charisma, leadership abilities and/or other variables you find in great people.
We really don't have much reliable information on how good famous people in history were at fighting on an individual level, quite frankly. To the extent that we do, we also have examples of women who were good. As one would expect for a variety of reasons, this number is far smaller than the number of men. But of course, the Dragonborn isn't composed of the average statistics of his gender and ethnic group so going by statistical norms is silly.
And yeah, upper body strength is the biggest factor. Were you trying to imply height was a big factor? Well, height IS a factor in combat, but the thing is, the variation in height between men and women is much smaller than the upper body strength variation. You can easily have tall women, so using that as a reason to not allow a player character be a women is quite weak. The same applies with upper body strength, but it the difference is bigger so more women are at a notable disadvantage here.
Studies regularly show that while the average women is less capable than the average man in this regard, there are still women who meet the necessary qualifications. One shouldn't confuse the differences between some averaged metric in two groups with the differences between individuals, otherwise you'll liable to say stupid things like "there are no tall women."