"Singular they" had already been the standard gender-neutral pronoun in English for hundreds of years. However, in 1745, prescriptive grammarians began to say that it was no longer acceptable. Their reasoning was that neutral pronouns don't exist in Latin, which was thought to be a better language, so English shouldn't use them, either. They instead began to recommend using "he" as a gender-neutral pronoun.[1] This started the dispute over the problem of acceptable gender-neutral pronouns in English, which has carried on for centuries now.