The problem the tumblrite crowd has with war vets and PTSD is recognition. If a war vet were to walk up to you and say "Hey man, could you turn that movie down a little, it reminds me of Iraq.", you'd likely turn it down.
Well, to the typical tumblrite, that's power. They turn around and cargo-cult it into their own little world, and we see crap like "trigger warnings". Invoking the magical PTSD works within the closed circle of the Tumblr cult, but outside of that, everyone is just going to laugh.
That's what pisses the typical tumblrite off. The PTSD ritual doesn't work when they invoke it on normals, and it makes them mad...whereas, the combat vet actually suffering from PTSD gets all that "power" and empathy.
I imagine it's also hard to prove, especially over the internet. If you know the basic symptoms, you can just lie about having them.
There's plenty of civilians with PTSD, but another thing I think Tumblrites do is they conflate trauma with PTSD. It's like comparing being anxious with having anxiety. Like, by Tumblr logic, I could say seeing a pet store tarantula when I was five gave me PTSD and seeing them triggers episodes where I feel sick and like, totally have flashbacks, man.
But I don't because that's fucking stupid.