This is really dumb, however it is a little exaggerated. It's not thatttt bad. only really happens to me if I'm pking a tower with 3-4 people. I'm pretty sure if you kill someone X amount of times , kills stop counting on that person., to reset the kill count you need to kill X amount of different people (it's definitely more than 2-3). I don't believe it's time based but not 100%.
I have seen a lot more active tower pkers than usual recently, so that is a positive at least. It's much more encouraging to pk when everyone else isn't boosting