Women in the military have various costs; pregnancy, modification of equipment, lowering of physical standards.
Justifying having a entire group, or sex purely do support roles is inefficient, and directs resources. You can't take a female clerk, then send her downrange to lead a raid or ambush. You can with any male marine, the key is interchange, you lose that by having two sexs. Especially now that the battlefield has expanded.
Yes, I would agree that, in the main, the military would be more efficient with fewer women. I think women should largely be limited to stateside support roles. However, I am a realist and that is never going to happen. So, women will be put in harm’s way and it’s just a matter of how much our political/military leadership is willing to make that more probable. Yes, I know the battlefield is expanding. Being in the “rear with the gear” is no longer as safe as it used to be. I do think that opening up combat mos to women will greatly expand that risk and reduce combat effectiveness. So, I oppose that move.