It’s all about balance. If someone had killed Hitler, would something worse had taken his place? Or, how about in Australia where a fence was constructed to keep dingos out of the south. But dingos are a predator to kangaroos so the kangaroo population increased and now they are overpopulated. Butterfly effect kind of thing.
> If someone had killed Hitler, would something worse had taken his place?
Unlike Hitler, there are countless mosquitoes. That enabled scientists to do controlled experiments. (Something the Australians didn't do with the dingo fencing, either.) I don't have a strong opinion on this measure. But before supporting or criticizing it, I would at least glance at that evidence.