Or, their play style is more cautious than yours and they value placement over kills - no matter what the ever-changing point system is rewarding this particular season.
So maybe they're sitting in their good position, with good kit, waiting for the final three, and thinking the entire time that their third teammate is so childishly impatient that he's willing to die in an obvious no-win, one-on-three situation. Thus costing them the full squad they would like to have for the end game.
In the end, rp and kp aside, every individual player has to decide for themselves whether kills are more important than a win. And, in my opinion, kills are a pointless statistic that people latch on to so they can make themselves feel better when they lose. Because, after all, a guy who gets ten kills in a match and finishes in second place... sure, he get's points and he ranks up. And is still a loser.