Style is a choice, not a question of right or wrong
Writers and editors have had the rules drilled into their heads. They have suffered from the pointed criticisms of other editors or writers, and they pass on those attitudes to the young writers they encounter.
We call these rules “style.” But style is not engraved in stone. It is simply conventions accepted by a group of writers or academics or professional groups.
The Associated Press promulgates style rules that are generally accepted in the newspaper business, through its “Associated Press Stylebook,” although different newspapers have their own exceptions to AP style.
Different writers prefer the Chicago Manual of Style or the American Psychological Association's style, for example. These different versions often don't agree.
One style war is over the use of “their” and associated plural pronouns to refer to singular subjects. “Someone has lost their marbles” is perfectly acceptable to some, but it gives me a bad feeling in my stomach. I prefer “Someone has lost his marbles” or “Someone has lost her marbles.” Or “They have lost their marbles.”
Spellings also can differ. For example, is it “horsefly” or honey fly”? It makes a difference to those who study honeybees. Here's an interesting look at it from their perspective.