Why does battle high exist?

[OskarXCI]

It's there to reward those that play well.

You normally get/lose +5/-5 points for killing someone/dying. The trade off for Battle High/Fever is that if you die with the buff, there is a bigger exchange of points. If you kill a Battle High player, you gain 10 points, they lose 10. For Battle Fever, it's +15/-15.