I have thought about this before; but the idea of having to update a scoreboard every time a creep is killed is pretty lag-tastic. Saving it to a variable and stuff wouldn't be difficult at all. In fact this is how simple it would be:
A unit dies
Unit is owned by neutral hostile
set UNITS_KILLED(Player number of (owner of killing unit)) to UNITS_KILLED(Player number of (owner of killing unit))+1
BAM, and it is saved.
The problem comes with presenting the information, and saving the variable every time a creep dies. CHA has wayyyy too much shit going on, and everything I add leads to possible game crashes for shitty players, and lag spikes for less shitty players, and many lag spikes for wrathbot.
If it were a -kills thing, it wouldnt be bad. But then only like, 1 outta 50 players would use it. and what would be the point of this? to announce "I carry my team" wouldnt that be shown in the fact that you have 3X their items from stats? to make it something actually viewable on a scoreboard (the less-asinine way to do it) would be toooooo laggy.