Leaning on Chaucer isn't sufficient, because it was once a pronoun used for people:
https://en.wikipedia.org/wiki/It_(pronoun)
So maybe we should bring back it, or ignore Chaucer as an authority.
The point isn't that we should all speak like Chaucer, it's that singular they isn't a new thing within our lifetimes.
The point isn't that we should all speak like Chaucer, it's that singular they isn't a new thing within our lifetimes.