Some people write so clearly that they do not need editors. But most of us can do better, and most organizations that think they don't need help with the writing they put out are fooling themselves.
Unclear writing costs money and reputations.
A prime example: A writer has the meaning of a sentence clearly in mind, but it does not show up on the page. This, from the New York Times:
"The father of a teenage girl filed a lawsuit against three police officers in Loveland, Colo., who arrested her in 2020, saying the men used excessive force when they slammed the 14-year-old onto concrete, fired a Taser at him and choked the family's Jack Russell terrier."
Huh?
The phrase "fired a Taser at him" follows immediately the phrase "they slammed the 14-year-old [girl] onto concrete." Doesn't the word "him" challenge you to try to figure out what's going on?
You have to work hard to see that "him" refers to the girl's father. Hard work is the writer's responsibility, not the reader's.
Solution: Place a period after "they slammed the 14-year-old onto concrete," and start a new sentence with, "Her father also said the police fired a Taser at him …"