This was famously the view of Social Darwinists. Herbert Spencer, for example, argued that nature should eliminate the weak. He said: "If they are not sufficiently complete to live, they die, and it is best they should die."

The most notorious case was probably Dr. Harry Haiselden, who refused surgery for some newborns with severe defects because letting them die was good for the species.

But, again, this is a philosophical/ethical argument. I believe that, in general, if people don't want to die, we should help them not die. I get that utilitarians are uncomfortable with that, but that's why I'm not a utilitarian.