Not just Mattis. He tried to order the active duty military to go after protestors in D.C. They reminded him of their oath and the Posse Comitatus Act. At volume. In the Oval Office. Then they released a force wide memo reminding everyone their oath was to the Constitution, not the President.
The military has a lot of bad things. But they are loyal to their own moral code. For an organization mostly made of people who wandered in from the street desperate for money or glory, I think that's pretty neat.
That's probably like 60 percent of it. They've definitely got internal problems like their sexual assault, suicide, and burn out rates. Also it can be a pretty toxic environment if you aren't a lean runner body type or don't conform to their culture. There's also a gang problem on some bases. So yeah, they have bad things going on even without politicians giving them screwed up orders.
Fair, it's basically somewhere between school and prison so those kind of environments breed that behavior, hard to keep that many young men together doing physical effort without the hormones getting unpleasant.
Still, other countries often handle it better so it's clearly possible, we also should raise our recruitment standards but the war on terror put paid to that.
We actually tried to raise our standards. Or rather, we stopped scraping the barrel under Obama. Biden then tried to digitalize the medical in processing. That had the effect of not allowing people to hide their previous medical adventures anymore. That's why recruiting fell off a cliff for a couple years and all those scare mongering headlines got printed. Thankfully most of the issues were stuff they wanted to waiver in anyway, like childhood asthma that's no longer bothering the recruit. The problem was people had to wait months for those waivers and by then they had already moved on. So now the waivers are fast and we're filling the ranks again, with a digital system preventing real medical issues from making it through.
But yeah, they stopped the "anything breathing" policy around 2010.