Disclaimer: "you" is meant to refer to the player. Not specifically you, Gaurdian. That's why Bungie is adjusting the mercy rule and score to win. My best guess on why someone would leave a match, the way you have worded it, would be due to the stress of being at a great disadvantage based on skill level or weapon choice or mental state, etc. In other words, your team is losing or you aren't doing particularly well. You've got a few choices here: wait for the mercy rule to kick in, take the penalty for leaving, or just deal with it and persevere, learn what you could improve on, and try a different approach to the objective/map. Besides, whether you win or lose, have a good or bad performance, you still get the rewards. If you get frustrated with the game, don't just leave the match, switch games or shut the console off and cool down. And the ultimate alternative: don't play in the competitive playlist and stick to quickplay. If the issue is that you want to play countdown or survival without the penalty of leaving; again, don't leave, and campaign in the forums for more playlists that include non-competitive versions of those gametypes. Or just wait for private matches.