It's not about capability, it's about value.

Women's lives are valuable, men's are not. This has been the case across basically all societies in human history. Losing a ton of men really doesn't matter too much - especially young, family-less men.

Losing a lot of women, though, is really really bad.

I was informed that we are all equal. Plenty of wartime occupancies carry no risk of dying, like being a nurse