Growth of 2-3% in anything you are actively work towards is the baseline success expectation as it is stagnant or declining otherwise. That is the equivalent of losing a decade's growth. Losing 20% of your salary would certainly qualify as losing 6 to 10 years of minimal growth expectation. It is twice that of a literal dictionary definition decimation. "Plummeting" is certainly not hyperbole.

Even a 10% can rightly be considered a "plummet" in many business contexts.

If a stock drops 10% in a day, that's gigantic. Considering how precarious the profitability of news organizations can be to begin with, a 10% drop that can't be reversed could be the difference between staying in business and folding, depending on how costs are structured.

If your traffic decreases by, say 10%, that's huge -- that's a plummet. (If your traffic decreases by 80%, you don't need adjectives anymore -- you're probably out of business now.)

Could you link and/or clarify a little bit? Did their profits shrink by 20% to 80%, or by 80% to 20%?

Their traffic went down by less than 20%.

Oh, under one fifth? Peachy.