If for nothing else than to get an actual view of how all the different builds are stacking up vs each other. Raw numbers don't tell us anything without the context of how many players were using X build or weapon Y. A single round won't tell us anything either, but over time patterns will become clear.
Also, in the interest of actually winning rounds and gaining multipliers, this will tell you who is really doing the damage to your team. If you look at the scoreboard to go headhunting to provide your team a better chance of winning, and yourself a better chance of getting a multiplier you want some way to tell who is causing the most harm. Right now, it can lie.
For example, a couched lancer pretty much gets 1 hit kills. They might go 20-1 over the course of a game and do, lets just guess an avg of 60 per kill or 1200 damage. An unlucky archer might be hitting everything in sight, but not actually ever get a kill. They could do an average of 20 damage per arrow, land 100 hits, but go 1-5 on the scoreboard. However, they did 2000 damage to the other team during those rounds.
Those numbers are pure fiction. We don't know what they might be. But lets pretend they are real, who would you headhunt? The armored lancer who can run away forever, or the squishy archer you can run down with your pony? Suddenly an otherwise anonymous archer is dead, their team loses a cumulative 2000 points of damage over the rounds and they don't understand why they lost their x5 when they were rolling the shit out of the other team.
Lets get the damage numbers up there along with the kills so that players can make a more informed decision about which enemy to hunt down in order to give you the best chance at a multiplier.