Anonymous“When did singular "they" fall out of use and why did prescriptvists "ban" its use?”
I was struck by the tone of the question, which sounded to me a little like an exam question.
I think this is because the question involves several assumptions:
1. That singular "they" fell out of use.
2. That it was "banned".
3. That those who "banned" it, if it was banned, were "prescriptivists".
4. That those who "banned" it, if it was banned, provided reasons.
All these assumptions,
if true, imply a detailed knowledge of the history of English usage on the questioner's part; though the putting of the question would seem to disavow any such knowledge.
Hence its formal likeness to an exam question: where of course the questioner does indeed "know" the answer already.
MrP