Because men and women are different? And a pretty important difference is precisely the fact that women don’t have “a pair”, to use your language.
Discussion
That used to be the case, but with the advent of feminism I've seen plenty of women with bigger balls than most men I know.
It’s true that Feminism has had many negative consequences. The social acceptance of gender dysphoria is just one of many. However, wouldn’t your suggestion be the third wave feminist position? I only point that out since you seem to imply a criticism of feminism while also taking that opinion.