DRK play is mostly fine.
The biggest problem is DOT stacking and AoE stacking.
If they capped number of targets for an AoE, and then did %-based damaged, based on how many are hit, then it would be a LOT less of an issue. e.g., damage is, say 100% for the first target, 75% for the second target and then say 50% for all subsequent other targets hit to a maximum of 5, have this same application apply to draw-in effects.
I can accept there is rudimentary strategy involved in doing the follow-up, but this rudimentary strategy should not be the effective reward of 4 people being able to annihilate 2 parties worth of people.
And it's all well and good saying "Just avoid it" -- Yes, a lot of people are capable of avoiding it, but a lot of inexperienced people are not capable of avoiding it or too inexperienced to do so. So even when I avoid it, if 13 other people don't then they're quickly stacking up BH. At which point they can just play more objectively.