I don't believe that people have zero responsibility for themselves.
I work in the emergency services. - PTSD is not something an individual can take "responsibility for". - You don't know if you will get PTSD until you actually have it... And by the time you have it, you cannot take responsibility for anything as you are NOT in the right frame of mind.
If a company/business/organization is exposing individuals to content which may have the potential negative effects either in the short or long term, then they should have the support in place to assist said exposed individuals when the time comes, it's as simple as that... And that should remain true regardless of the field you work in... PTSD is not something you should eve take lightly.
And sorry to burst the discussion, but yes Military don't enlist expecting PTSD but they know that is a possible occurrence and mainly they know they are likely to enter battle and kill or die. Same way when you enter a company that makes Mortal Kombat that since the 1st game were about gore and violence you have to expect to be exposed to it.
In saying that... You join the Military knowing/hoping that the support exists in the event you may get PTSD.
Video games is a relatively new field though, so the support for workers being exposed to questionable content simply doesn't exist yet... Where-as the Military has had centuries to build the appropriate frameworks to support it's workers, same with other fields.