Well Zergfights may be “somewhat” balanced against a Necro, since you´ll get alot more cleanses from your team. The problem arises in small-scale roaming environments, where button-spamming shouts with Rune of the Reaper and going into shroud (auto-traits Hydromancy) alone stacks more then 25 bleeding along with all the other abilities applying chill. A profession or well, spec, that´s focused on corrupting, denying boons and holding condition pressure while building as tanky as possible shouldnt be allowed to instakill enemies, which is only accessible to high-full dmg specs/professions building with low defenses, eitherways.
To throw in some numbers, permanently creating ~3-5 conditions with 10 s base duration (goes for most corrupted boons) alone is strong, having ~10 bleeding tick meanwhile would be nice and somewhat healthy pressure, but instead it is 30 and forces you to spam all the condition cleases humanly possible to not die in 3-5 seconds.
Yea Reapers 1v1s maybe are not the greatest, but what do you expect from a, somewhat supportive build. The amount of counterplay against it is plain, like, as in hardcounter or die.