And here is why: She was an atheist, and no objective, absolute morals can be ordained by Science alone. It seems to me that she never advanced a cogent response to one of her own characters, Cuffy Meigs, who said: "In the long run, we're all dead."
Plus, reliance on Science alone must lead to the conclusion that all actions are simply the result of cause and effect, that is, chemistry and physics, in the end. There is no free will under Science. It is pure determinism. If a person has no free will, then there can be no morals at all.
The greatest threat to humankind is Left-Wing Socialism.
Choose sides.
Actually, that point of view about science went out the window with the advent of the Heisenberg Uncertainty Principle.