"all the coastal cities" rephrased into "every coastal city"

"Guys, please be quiet; if you're all talking I can't teach."
"Guys, please be quiet; if every single one of you is talking I can't teach."
You can't see the difference? One is generalized shorthand for "those of you who are talking," while the other is explicitly including each individual.
"All the coastal cities," especially given the context of the phrase and the tone of it, is shorthand for "A significant number of coastal cities." The paraphraser purposely altered it to "every coastal city" because that is a more absolute statement that sounds ridiculous.