for those that argue against singular they
some people love to say that they refers to multiple people. a popular retort is that singular they predates singular you. on that topic i very much enjoyed finding this source: https://public.oed.com/blog/a-brief-history-of-singular-they/
singular they dates back at least since 1375, nearly 650 years ago. you as singular was argued against in 1660.
so roughly we can say that singular they predates singular you by 300 years.

















