@gav @BadFediPosts you remember a thing from elementary school. Are you literate? Have you read books? Books written by dead people? Lots of books like that?
'They' is a plural pronoun which gets apparently singular use only in deliberately ambiguity where even the number of subjects is unimportant. If you're telling a story about how "the police came to talk to me", it's unimportant to the story that it was two dudes vs. a single woman - it's much more important that police of any kind are talking to you about something, so you gloss over such details.
Singular 'they' was always sloppy but very rare because it was always rare to be that vague. It was never an explicitly gender-neuter or gender-neutral pronoun. The better word for that is 'it'.
Singular 'they' is used all the time today only because gender-ideological freaks have made people so habitually afraid of referring to even clearly observed sex, that people just don't do that, and will say "they" even about a subject introduced as a "woman" and earlier referred to as "her". Insane people are breaking English because normal English grammar breaks the delusions of the insane people.