And the definition does matter, because 'famine' has the meaning of a certain level of bad thing happening. If we do not preserve the meaning, then the word will not have a meaning, then we have no more word to talk about that bad thing, so we will pay no attention to averting or fixing the bad thing because we don't have the literal ability to talk about it.
I'm in favor of being able to have a productive discussion about famines and how to avoid them, so I'm in favor of having a word for 'famine' with a clearly defined meaning.