I think the better measure of how much someone has worked is either number of hits or number of points gained. Farming does take effort, and counting kills is a double-edged sword; it could be someone putting in effort to defend their team and self, or it could be a person not cooperating with their team and killing off every farm on sight.
I don’t know if you meant this or not, but number of POINTS sounds slightly unfair—users can, after all, donate points. Number of points GAINED would negate this, instead rewarding farms.
Also, number of revivals could be a factor—it’s hard to deliberately kill your teammates, and when such a deed is done it generally does not come with the intention to revive them afterwards.
I fully support this suggestion otherwise, though. Hope it gets added.