All the professional mercenaries out there know each other or of each other, and with death being less permanent, killing is not the easiest option anymore. And in fact can serve as a missed opportunity because there are organizations that pay out ransoms, and with the right insurance, it is guaranteed that the right email or phone call can insure the right transfer of funds to certain secret offshore accounts that technically do not exist. Of course there's always the chance that the dead rival could come back as something much worse and more powerful than any mere mortal out there...