The Marine Corps established the CFT (Combat Fitness Test) a few years ago, because the PFT does not accurately show how one would do in a combat environment. You do the CFT in cammies with boots, not pt shorts, a t, and running shoes. While it is a step in the right direction, it still can't come close to how hard it can be living on the edge, patrolling every day.
As the article linked showed, women just break down faster than men. Their bodies simply aren't built for it. Over time, who has always done the heavy lifting of jobs, throughout all over the world, and time? Men.
The physical part is not all of it, there is so much more than that to deal with. While I do think it sucks for the females who really want to do it, and think they can, it's not worth it letting the very few who could pass. I don't feel like finding the article (was in Marine Corps times), but it took a fitness instructor 3 years to achieve 20 pullups. Which is what men do. Took me less than 3 months of boot camp. She was pretty built too.
During a few operations, myself and another combat engineer deployed APOBS several times. If you don't know what that is, it is a two pack of grenades and a rocket. Basically you attach the packs together, the rocket shoots forward, and the grenades blow up. Making a clear line to walk. There are 108 grenades in total, then the rocket. The system weighs around 125lbs. There are two packs, then the rocket bag. Nowhere in the CFT do you do anything this hard. I set off four of them, under fire, having to low crawl a few times. Getting up off the ground, with all my gear on, PLUS a 60lb pack of grenades was brutal. I am not trying to sound like some billy bad ass. But it was the wild west out there, and we did some crazy shit. We were Ospry dropped in on the biggest offensive in the Helmand provice in the middle of nowhere. No support for two days. We only took a handful of water bottles with us. Supposed to get resupplied the next day, helo's couldn't because it was too hot. Totally exhausted and dehydrated. We got hit hard because we had no support, and they knew it. But we had to take this one huge hill, and put up the snipers and machine gunners to take the bazaar. Know what a MK19 is? Try carrying that, it's about fucking impossible with all your gear on over any distance, and especially up a moon dust hill, but we did it. That, and a M2. I am telling you with all seriousness, a woman would have been a hinder that day, and there is no way she could have pulled her own weight. I have tons of stories, pics, vids, whatever. I don't care if anyone believes me. Messing with the dynamic of what we had with one, or two females would have been a terrible mistake.
Again, I am sure what we did was on the far end of the scale. Most deployed Marines don't do anything like that. Most deployed troops sit on a big base living the cushy life. But still get paid hazard pay and everything else. Don't even get me started on that. But to me, it is just not worth it to get the hard charging females a chance, to have to put up with all the rest of the baggage that would come along.