greengrocer's apostrophe: An apostrophe used incorrectly to form the plural of a noun through ignorance of the use of the apostrophe.
I was under the impression the people who differ are just uninformed of the correct grammar.
English has not been spoken with the correct "grammar" in the past 500 years. People keep speaking English in the way that makes sense to them, and eventually the "grammarians" catch up.
The grammarians used to say it was incorrect for you to boldly go forth, to have an agenda, to note what the data says, to find a free seat, or to have a fun time. This sentence would be frowned upon by grammarians of the past. But, once something makes enough sense to enough people to become common usage, it becomes correct.
English belongs to the "greengrocers".