No, "you" is also indefinite. You can refer to an individual or a group. "Thee/Thou/Yee" was abandoned in lieu of "you". "You" wasn't even used as a subject, at all. "You" taking over the context of pronouns no longer used has nothing to do with the mentally ill trying to avoid single person pronouns altogether. So.....still wrong, but keep trying.
Still incorrect. "You" is used as both singular and plural, and as both definite and indefinite. However at this point, I'm done trying to confuse you with facts. I've provided the links to the lingual history of the words. I've shown that words evolve, such that even if singular "they" wasn't applicable before, it can certainly be now. I have given you the water, but I can't make you drink.
*shrug* If Suzy wants you to refer to her as "they" knock yourself out. Virtue signal as hard as you want, I don't really care.
When I initially replied to your thread, my impression had been that this was a fairly limited phenomenon, which the Right was blowing up, all out of proportion. But I just registered for a blood-drawing appointment, at Quest, and one of the few, basic questions, after my sex, was my: "gender." WHAT? Why would that be relevant, for a blood test? So they will know, whether to call me "sir," or "Ms.?" That shouldn't be a problem, because in all of my visits there, no one has ever even referred to me as "sir." This does seem to be getting a bit ridiculous.
In situations where you don't know the gender of the singular person you're referring to, you might use "they", but that's only because it doesn't carry the negative connotation that saying "it", which would be another term to use when gender is unknown, seems to have. But it's still stupid grammar that makes you sound like you don't know how to talk.