The issue isn’t whether women can physically handle serving in a combat unit. I have no doubt some could.
However, it has to do with unit morale and cohesiveness.
Serving in an infantry combat unit is dangerous, and being such, dangerous jobs like being on point, are shared.
Now consider that you have women in a combat unit, and Mary is attracted to the platoon Sergent and they end up in a romantic relationship. Now, the unit is sent out on patrol, is he going to put his sweetheart on point? Then consider, the relationship falls apart, and Mary now is going out with PFC Brown. Now the unit goes out on patrol and the now jealous platoon sergeant wants to get rid of PFC Brown, so he constantly chooses him for point and other more dangerous assignments.
Now even if the platoon sergeant doesn’t become jealous and doesn’t make PFC Brown do more than anyone else, the platoon will have the knowledge of the former affair between Mary and the sergeant and will always be suspicious of his motives.
I saw it happened in non-combat units where affairs between women co-workers and managers went on and the woman received special favors that the others didn’t get.
I saw it happen way back when I was a young teen in Drum and Bugle Corps, when we went from an all male corps to a mixed gender corps. When the girls came in, the unit bonding between the members fell apart an we even lost the top horn players because the affair he was having with one of the females fell apart and he couldn’t stand seeing her with another member of the corps.
If you believe this won’t happen, you have chosen to ignore the biological chemistry that goes on between males and females and I have to wonder what planet you come from where this doesn’t happen?
Jim