If confirming a kill that wasn't yours was patched to be worth nothing but a point for your team the this problem would be gone in a day.
It would also completely ruin what Treyarch was trying to do with Kill Confirmed.
The problem that MW3's KC had was that absolutely nobody confirmed their kills, preferring to play that mode like TDM with a higher kill limit so they could killwhore more.
The reason Treyarch made confirming someone else's kills give more points than getting and confirming your own kills was to pressure killwhores into playing the objective. Yeah, it's annoying when ub3rpr0sn!p3zzzz insists on doing nothing but running around with dual KAP-40s stealing everyone's tags and dying every 10 seconds thus rendering himself unable to build the streaks that you could've if you had collected all those tags, but that's honestly what Treyarch wanted: People playing the objective.
I wasn't suggesting it should be that way just noting that people defend tag stealing as objective playing when this is the same community that would avoid tags like the plague in MW3. People steal tags for personal gain and I hate missing out on my vSat so some chump can get his HK or CP.