Well, to start with, there's a cooldown on spirit loss after being murdered. If I remember the dev journals correctly, it's about 2 hours during normal times, but gets extended to 10 hours (Need verification) during wartime, because war can drive narratives, but if everyone thinks they'll lose out on several months of playtime because of a war, they'll be much more stingy with starting them. Even with a somewhat shorter cooldown, one would have to be pretty dedicated to getting themselves killed to suddenly drop their lifespan during that battle or a war that lasts a couple of years (weeks). And even that's assuming a CDG every time.
On the other hand, if it does happen...it's interesting from a story perspective, isn't it?