When is a perfectly good word not perfectly good?

I was reading the Sydney Morning Herald online and saw an article on the economy of the state of New South Wales, which has been on a more downward trend than the overall economy of Australia. The article said the state had posted three consecutive quarters of "negative growth".

The prissy grammarian in me paused at this phrase, and I could hear her start to think, "'Negative growth'! Growth is positive! There's already a perfectly good word for that, which is 'shrinking'. When something negatively grows, what it's doing is getting smaller, and there's already a perfectly good word for that in English! Gah!" My internal prissy grammarian felt a sense of indignant outrage.

But then the person inside me who wrote my PhD on how linguistic conventions are shaped by use in a social context over time, the one who always argues that rules can change and if a usage gets entrenched in a social group then it counts as the rule, reflected that the economic term "negative growth" really is different from the ordinary language terms "shrinking" or "getting smaller". Growth in this context is a specific thing that's plotted out on a graph and given a number. That number is positive, in some percentage point, or it can dip below the zero axis and be a negative number, but the thing being measured on the graph is still called "growth", so leaving that term out actually sort of changes the meaning. If you changed the statement from "The NSW state economy has shown three consecutive quarters of negative growth" to "The NSW state economy has been shrinking for three consecutive quarters," you rob the statement of a degree of economic precision, and and change it into a looser statement in ordinary English.

So I am not entirely outraged by this term. I can see arguments both for and against it.