I think all Raid encounters in anygame the goal is to have no one to die and kill the bosses Forcing someone to die is sort of dumb unless it is a mechanic of a boss like kill the tank because boss hits X % and changes phases and kills tank in anger etc.
This won't cause weakness due to it being a mechanic supposed to happen and doesn't cost any repair again Due to mechanic. but again people aren't actually supposed to die in boss fights.