KDA is all the matters, halo is not a camping game in the sense that it is hard to camp, and even if you do, you can still lose fights because you don't die in 1 hit.
It promotes team play since you can bait/team fight someone
Camping persay is different in halo in that you KNOW where the other team is camping, they take a strategic map location to "defend" or set up so that they won't die or can escape to their team.
There has never been "camping" in halo like there is in COD. Yes teams would set up at Pink in Halo 2, or Big Base or Little Base. But you knew where they were "camping" and could adjust accordingly
The amount of kills you get is not how you should be ranked. You can get 49 kills a game and die 49 times, and still lose.
KDA is what matters. You cannot win if your team average KDA is not higher than the other teams.
Obviously there is some weight to kills