and you got the response from us.
In a world where killing is for survival, and a means of getting what you need just not to die...I cant see any ingame reasoning why people would keep a 'killboard' of who they killed in the context of the game.
Storybased, killing would be for the most primitive of animalistic reasons..defense, acquire much needed items, or rivalries over desirable assets..in that setting where trying to scrape by a living, I cannot see anyone wanting to carry around a board to show other new people that meet how many people that they killed that day.