Well, murder and physical teasing is most certainly a false equivalency, but I see your point. To answer your question as to who decides when enough is enough, the individual does. No one is forcing anyone to remain in a friendship group. In my example, the guy could have left at any moment or called it off. If he had, that would have been the end of it. It's always consent-based, that's the whole point.

But I agree that there are actions that take this to an extreme - some of which I mentioned. I personally know lots of people who embarrass and tease each other to a level that I think is way too far... so I'm not friends with them. Simple as that.

As for your platoon, that's fine as well. It isn't needed for all groups to function, this is just a trend that I have noticed; in my experience with soldiers, it is *very* common. But, of course, it's different strokes for different folks.