I think they want to be able to kill doctors without having to pack a lunch. After the first five minutes of the battle you just want the doctor to go away.
Granted, the following isn't an issue with CH, but I have the same problem with TL7 docs and their massive and quick heals, either kill me quick or move on. I don't expect them to roll over and die, but at least let me move on and do something productive with my time. I really don't enjoy feeding bullet after bullet into a doc for 20 mins hoping he makes a mistake or one of us dies of old age.