ALT TEXT:
- Panel 1: A person with the text "Singular 'they'" written on them smiling with open arms.
- Panel 2: "Singular 'They'" beaten up by others who said, "Singular they is ungrammatical. It's too confusing," "How can anyone use plural pronouns for singular," and "Every pronoun should only have one purpose."
- Panel 3: "You" hiding from the mob who was beating "Singular 'They'"
- Panel 4: "German 'Sie'" hiding with even more fear next to "You"
The root of the problem is that it's an indirect reference to an individual. They/them is commonly (until very recently) referring to a party (singular or plural) that isn't present. When you use it as a direct reference to someone who is present, most people feel like it's incorrect because of the common usage of the term being indirect.
When speaking to someone about Joe: "Joe doesn't know what they're talking about" While directly: "Joe, you don't know what you're talking about"
Both are correct, and possibly the most correct forms of the statements. Substitute Joe for whatever name and it still works. Meanwhile, it's uncommon, in Joe's presence, when not taking to Joe, to refer to (assuming Joe is using gendered pronouns) him as a he/him. "Joe doesn't know what he's talking about"
Both cases are singular, but the difference of Joe being there changes "they" to "he", and not taking directly to Joe changes "you" to "he".
The problem isn't plural vs singular, the problem is direct vs indirect reference.
To the best of my knowledge, using pronouns like he, she, they for a person who is present in the room during the conversation is not part of the most recent change to the singular they. That would be confusing, but I am not aware that that is happening. He, she, and they are still only for indirect references to a person as far as I know.
I don't think you're wrong here; it's just uncommon to refer to someone as they/them even indirectly while they are present and engaged in the conversation that's happening, but may not be the directed recipient of the statement. In almost all cases, at least until recently, the pronouns he/she or him/her would be used instead; therefore it's sort of awkward to use it as a direct pronoun in that context; but using they/them as a direct singular is not new in any capacity and I believe you're correct on that. It's just uncommon, and IMO, would generally come across as mildly dismissive or insulting toward the individual in question.
I believe the (former) dismissive/insulting nature of the context of referring to someone as they/them directly is the root of the discomfort most people (especially cis-normative persons) have around using the term for direct reference of a singular individual. Their brain is uncomfortable at the fact that they're using (mildly) offensive language towards someone who they likely mean no offense to, meanwhile to use he/him or she/her instead is likely going to be far more offensive to someone who is non-binary, so the discomfort only lies within the speaker and their expectation of how what they are saying will be understood.