It's a tough one. There shouldn't be a stigma around mental health issues, or asking for help...but there is also an issue with people using it as an excuse for bad behaviour, or to gain some benefit from it. Sadly, it does mean that there can be a bit of cynicism when someone gets themselves into trouble and then claims a mental health issue. I'd like to think most are telling the truth and wouldn't stoop so low as to claim a non-existent condition to get off the hook...but I also know for damn sure there are people who do stoop to that.
I have a sibling and a cousin who have, every time they front court for viciously assaulting someone...and it's an issue in the military as well. Can totally understand PTSD and why it's become such an issue in recent times...but if, during your deployment, you never left an air conditioned office in a safe country...yeah, I'm a little skeptical. Easy way to get a medical discharge and a pension if you play it right. Plenty who deserve that, but also a subset bunging it on and milking it for all it's worth...