I think that referring to a non-specific indefinite person like everyone, anyone, someone etc. as "they" is grammatical and widely accepted as being natural at least in informal speech.
For example, the sentence "Everyone did their best" is grammatical.
However, what about referring to a specific...
@δοῦλος You don't seem to understand the question ."Somebody" is a non-specific indefinite person. And I said clearly that referring to it as they is grammatical.
Okay, forget about that. The more important issue seems to me to be Can you understand the answers in my answer post? If not, I will be glad to clarify it for you.
I will not reset my close vote, because your question is still a possible duplicate.
I charge up to $50 an hour to teach ESL, sometimes more to proofread. I do not appreciate the guff that oftentimes accompanies your questions @MakotoKato. However, if you want a professional answer, trimmed with all the niceties that you may demand, I would probably deny you even if you could afford to pay $200 an hour.
Fifth, I do not know if you realize this or not, but your attitude @MakotoKato comes across as very bossy and even ascerbic. You should be grateful for any legitimate answer you get from a native speaker. This is a free service that people do because they are interested in answering questions from people who appreciate answers. For people who ask questions and then demand that answers "should" be a certain way, well, I will just say that not every native speaker is going to bother providing an answer of any type for someone who has this kind of attitude.
The acceptability of certian phrases, including the Singular they can INDEEd change in 30 years. Singular They is much more accepted now then it was back 30 years ago
My skype id is Sp3lly, if you wish to discuss this in private via Skype. I would like to get to know you better. Sometimes misunderstandings can occur in an environment such as SE which offers little room for open honest communication.
Discussion between δοῦλος and Makoto …
Discussion between δοῦλος and Makoto …