I can vouch for this. I've done experiments to see how the point system works, and as far as I'm concerned, the person that gets the killshot gets the most points. I've stood back and watched players wittle down visceras to a sliver of health, before taking the kill with a crit from my VBI sniper. Nets me over 2000 points, for doing not even a tenth of the other persons damage. On the other hand, I've wittled down visceras to very low health, got into cover and waited for someone else to take the kill. Nets me on average 300 points, even though I did the most damage. As I said, I've done both of these on multiple occasions, just to experiment with it, and I agree with Arsenic on this.
I'm not complaining about kill stealers. I get the 20k I need about halfway through, if not quicker, and usually wait out the rest of the siege so others can get their points. I know if I run around doing damage they won't get as much as they could, and I'm trying to be fair to everyone.
As for the original poster, don't worry about people fussing at you for playing the game. Just try to be fair to everyone, cap out where you'd like to, unless you're really shooting to get the Stage 10 achievement. We are all players of the same game here, let's all be nice and enjoy it with each other.
P.S. Sorry to the few people I stole kills from, I wasn't trying to be a jerk, just trying to make sure I was right about the scoring!