As a former SOCOM meat eater, I've been there and done that. Thank you for continuing the fight after I was sidelined due to injuries.
That said, conflating grief like this with in-game griefing is to miss the secondary
definition of the word.
And as someone who has a mental health professional as a wife, I can tell you that she and her colleagues have absolutely conducted sufficient research to back up the OP inasmuch as a limited subset of those who engage in such activity are mentally or emotionally disturbed. By no means is it all of them, of course, but it's a valid point. The online world, nowadays, is not entirely a fiction for many. Children of this era consider their digital goods to be as real, and of as much value to them, as anything else they own. Intentional bullying or harassment can be as damaging to many online as it can be to children in school or anyone else in other walks of life. It is not up to us to define for others the parameters of what matters to them. The freedom to do so is part of why you, I, and our brothers in arms fought and so many died.
Now, personally, I feel it's important to remember that each of us ought to own our own decisions and conduct ourselves as needed in order to avoid things which negatively impact us. It's for this reason that I largely game alone or with a close knit group of friends. It isn't that the griefers damage me emotionally so much as I have better things to do with my leisure time than deal with childish behavior. That said, I do agree some sort of karma system is called for. Heck, even Eve Online ended up having to do this in the long run. Many may not remember the days when security status was hardly even a big deal in that game, but I do. I remember when someone with as low a security rating as was possible could, if they were careful, freely roam the systems and Concorde generally didn't do much to them if they were careful. That changed, though, because the community demanded it. And Eve Online is a game where this sort of so-called emergent gameplay (or as I like to call it, acting like an ) is considered just part of the game. That doesn't mean it doesn't need to come with certain consequences, however.