Probably because it is the accurate term to describe any increase beyond simple singular replication."We have seen the start of exponential growth," said Provincial Health Officer Dr. Bonnie Henry.
I am trying to remember the last time that I noticed a mainstream US news source use the term, "exponential growth."
Quickly checking the NYT and WaPo I only can find: explosive growth, sudden growth, dramatic growth, rapid growth, mushrooming growth, snowballing growth, escalating growth, rocketing growth, skyrocketing growth, huge growth, & growing bigley.
I'm guessing they don't do the bacterial growth conquering the world or mousetrap and ping pong ball things anymore for kids...