Because the reasons men and women are better/worse at X/Y aren't just genetic, or even just biological.
Of course, biological differences do exist. For example, women have a higher pain tolerance than men because they have to give birth, but they can't hold as much in their bladder (compared to men) because their bladder is surrounded by baby-making organs and a man's bladder isn't.
But biological differences make up only a small part of the many differences between men and women in our society. All the rest come from environment, mainly social conditioning. Studies have shown that
babies as young as 10 months old have already learned some gender roles. In other words all of us, before we were even a year old, had already started building our internal template for what it means to be male or female, based on the templates of people around us ... templates which came from a long history of inequality.
No one (sane) cares about "equality statistics" when they're about basic biological differences. But the problem is that throughout history people have blamed socially-caused traits on biology, not just for women but also other groups. For instance, so-called "scientists"
blamed the shape of African-Americans' heads for their inherent biological mental inferiority ... even though there was no such "inherent biological inferiority" at all (as real scientists would later prove). What was perceived as a biological issue was in fact entirely a product of environment.
Likewise, women today are prevented or discouraged from doing things, even if they can do them as well as men. The only way they can show that they're being prevented is to use facts and information, eg. "equality statistics".