I am a firm believer in the Socratic method (forming and guiding discussion by asking the opposing side questions to stimulate critical thinking). As such, even though I am firmly against phrases like this no matter the context I will make the effort to understand the opposing viewpoint, if there is one.
For me specifically, I have had friends and family (though thankfully never myself) emotionally compromised and thus have had too many moment where a phrase like "go kill yourself", no matter how lightly used, would have actually resulted in a death. Luckily this never happened, but I have been right there in the thick of it; where words and how they are used hold more power over a person than most would care to admit. Where what you meant and your intent of your words mean jack all, only the results. My experience in life has given me a profound respect for communication towards other people, and while I cannot say I have been perfect, I do hold myself to a high standard when it comes to talking to someone else, in-game or out. As well as a profound respect for a life in general.
At the same time, I also hope my experience is not a common one. I hope that very few of you have had to deal with a loved one losing all hope or a friend being placed on suicide watch. I do not expect the average person to truly grasp my view without these experiences, and I do not wish these experiences on anyone.
(tl;dr)
So this leaves me hoping you can trust me when I say that I think anyone who types a death threat or another such phrase like that in earnest, that I genuinely think you have given up the right to speak.
#If you do not appropriately grasp what words like that mean, but use them anyway...
you obviously need to put more effort into understanding the implications of what you say. **Like a child in time-out. **
#If you realize the gravity of what you are saying, but say it anyway...
you obviously do not care enough to be able to communicate with the fellow human beings that you hold in such little regard. You are using words as a weapon and have no respect for the safety of the people around you, you need to have that weapon removed from your possession. Like a dog with a muzzle.
This is my honest, but individual, opinion. I recognize that I feel strongly about this subject and as such hope that the intensity of my opinion is meant specifically to convey that, and not to shut down the opinions of others.