I don’t believe it throws it off at all.
We have a thrall with several thousand health being killed. Which means they took several thousand damage in a timeframe where its master did not (either by choice or inability) prevent it.
We’re not seeing situations where a reasonable sized group (meaning not a careless or botched mispull) of NPCs just dump down a follower in one hit. But the collective DPS eventually whittling them down.
I will admit there MIGHT be a situation where the master simply cannot save their followers. But in those cases they are trying to punch above their own weight class. Not all content in the game is going to be achievable without some bit of resource cost, in this case, followers.
If the Mounds of the Dead, Sepermeru, and Volcano are resulting in unsustainable losses, there is plenty of areas in the map that have lower requirements and difficulty levels. Players have many opportunities to drop down as needed.
Unfortunately for many others, the oppositie isn’t exactly true. But that’s another topic to itself.