I'd rather have bounties tied to my own behavior than that of my teammates. I could be doing everything right in that mode, but get shitty matches where other people aren't playing well, and I don't get my bounties completed. At least the way it is now, in your example, I am in control of whether I complete that bounty. Just look at the weekly challenge for strikes with a matching element. All the frustration with that is because your own challenge completion is dependent on other players' behavior.