Battle high and fever is a good thing, rewards players who are killing / contributing a lot to become more powerful and a bigger threat to the opposing teams. (and a more desirable target to focus since a BH/BF death rewards more points -/+). Yes it can feel like a uphill battle especially if you go up against a premade who know how to actually play pvp however thats where you want teamwork; to focus those high prio targets and healers to get rid of their buff.

Despite the adrenaline and damage buff they get theyre still the same hp wise and can be focused as such. The better team should always win anyway so if one team has multiple BH and BF then it is what it is your team sucking or the other is feeding. I'd also like to add that if you know how to burst and use your awareness you can get battle high / fever yourself even without a healer backing you, its open to everyone who can last hit.