They/Them

What issue? I fail to see how that impacts you negatively in any way.

No no, hear me out.

So you're not, in fact, "super supportive" at all then, are you, and are not, in fact, worth hearing out.. 🙄

That comment did not imply any of this in the least

Well... that is entirely a you problem. You should do a little soul searching to figure out why it is so difficult for you to pay someone dear to someone you call a friend the bare minimum amount of respect.

Would you be upset if your friends constantly misgendered you, then acted like you were the asshole because you took issue with it?

Don't use it then.

The only time you would ever need to use someone's pronouns is when they're not part of the conversation anyway.

I couldn't care less what people refer to me as if I'm not there.

"I was with Dan the other day. They forgot their keys at home. They said they had to go back to get them."
Literally not hard at all?
- "I was with Dan (they/them) and Steve the other day. They hadn't brought a poster they needed and went back to the car to get it."
  This demonstrates the semantic problem with using "they" as a pronoun: it isn't clear who went back to the car, (1) just Dan or (2) both Dan and Steve. Nor is it clear who needed the poster and who hadn't brought it.
  
  You're going out of your way to create a problem that doesn't exist. Just Dan? Say Dan went back to the car. Both Dan and Steve? Say they both went back to the car.
  If you just don't respect people's identity then admit you're bigoted instead of hiding behind faulty logic.
  
  You're going out of your way to create a problem that doesn't exist.
  The problem does exist, that's why you're making suggestions about how to work around the problem. I've been confused before by people using "they" as a pronoun in exactly this sense. I'm not going out of my way to create a problem, it's a problem that I've experienced IRL. Please don't try to invalidate my experience.
  If you just don't respect people's identity then admit you're bigoted instead of hiding behind faulty logic.
  You're jump to conclusions.
  
  You're jump to conclusions
  Lol. Alright buddy, I'm done here.
  
  You're not going to bother to point out the fault in my logic?
  
  It's equally unclear if both Dan and Steve use "he", it's just the the options are "Dan / Steve" instead of "Dan / Dan and Steve"
  
  I don't understand what you're trying to express. I can't make sense of what you've written.
  
  If the Dan in your example used he/him pronouns and so did Steve, then it is equally unclear
  "I was with Dan (he/him) and Steve (he/him) the other day. He hadn't brought a poster he needed and went back to the car to get it."
  There's no way to know whether the "he" is Dan or Steve. The they/them pronoun isn't the problem in your example, the structure of the sentence is.
  
  There's no way to know whether the "he" is Dan or Steve.
  Your example sentence is always ambiguous because there is only one sense of the word "he" but two possible objects. My example sentence is always ambiguous because there are two senses of the word "they". The two situations are completely different linguistic issues.
  Your example is of a poor speaker. My example is of a poor pronoun choice.
  The they/them pronoun isn't the problem in your example, the structure of the sentence is.
  I disagree entirely.
  
  Dan (or Steve, or both) is the subject of this sentence, not the object.
  In both sentences, the pronoun used has two possible meanings in that context. That the two "they" definitions might be listed separately in a dictionary does not seem very important. It wouldn't even need to be separate, as "third person pronoun, indeterminate number and gender" would accurately cover both cases.
  What would be a non-ambiguous version of the sentence, in your opinion?
  
  Dan (or Steve, or both) is the subject of this sentence, not the object.
  You may be right about that (I'm not sure) but it doesn't effect the argument.
  In both sentences, the pronoun used has two possible meanings in that context.
  What are the two meanings (senses) of the word "he" in your sentence? It only seems to have one meaning from what I can tell.
  As I understand it, in both sentences there are two subjects (using your terminology) but in my sentence, the pronoun has more than one sense whereas in your sentence the pronoun has only one sense. The multiple senses of the pronoun in my sentence is the cause of the problem, not the multiple subjects.
  In my sentence it's also possible that there is the same ambiguity of subjects as in yours but that is not a given because it depends on which of the senses of the pronoun is intended. And that isn't clear. Which is the problem.
  
  What are the two meanings (senses) of the word "he" in your sentence?
  Dan or Steve is what I mean here — meanings within the context of their usage, not in an isolated sense. These meanings would both be described as "third person singular male pronoun" in a dictionary, but by the nature of a pronoun the whole point is for it to refer to something you've already talked about in context
  The multiple senses of the pronoun in my sentence is the cause of the problem, not the multiple subjects.
  We can test for this. If there's only one subject, Dan, then the sentence becomes:
  "I was with Dan (they/them) the other day. They hadn't brought a poster they needed and went back to the car to get it."
  No ambiguity there, it can only mean Dan. Similarly, with a single subject that consists of multiple people:
  "I was with the newlyweds the other day. They hadn't brought a poster they needed and went back to the car to get it."
  Exact same thing, no ambiguity. So we can use "they" in both senses and it's totally fine so long as there's only one subject. The ambiguity comes about when there are two possibilities already mentioned that the pronoun could potentially refer to — just like if Dan and Steve are both "he".
  
  If you're with Dan (they/them) and Dan (he/him), you would also have the problem when saying
  "I was with Dan and Dan the other day. Dan hadn't brought the poster, so Dan went back to the car to get it."
  So to avoud confusion, people should not be allowed to be called Dan anymore. In fact everyone gets a UUID so there is no more confusion.
  
  you would also have the problem when saying ...
  You would have a problem but it would not be the same problem as in my example. The problem here is not because of the choice of pronoun.
  
  Well it kinda is. Pronouns are like names, in the sense that we use them to describe to whom we refer.
  They are a non injective function on the name set.
  The restriction you would like to make is that the function is not multivalued. But it is. As an example, Andrea is a name that is usually associated with a female person, but it is a normal name for male people in Italy.
  We allowed people to be named whatever they wanted (or their parents wanted), so why not also let them choose whatever pronoun they prefer?
  
  Well it kinda is.
  I disagree.
  Pronouns are like names
  Pronouns are not names.
  allowed
  That's the second time you've used the word "allow". That's very telling.
  
  I disagree.
  I disagree.
  Pronouns are not names.
  Yes, that is why I wrote "like". They serve the same functionality.
  second
  That is the first time you wrote second. That's very telling.
The only time you would ever need to use someone’s pronouns is when they’re not part of the conversation anyway.
no? it would be weird to use in a one-on-one conversation, true. but it is fairly common to use the third person pronoun of someone during a group conversation, even while they are there
- I don't do this, and growing up was taught that it was rude to refer to someone by anything other than their name in a group conversation.
- it is fairly common to use the third person pronoun of someone during a group conversation, even while they are there
  But is improper to do so. The proper way to refer to a person who is present is by using their name.
  
  You don't use the person's name every time when you're talking about them in their presence. If I'm with my friends Mark and Fergus, and I'm telling Mark a story about something that happened to me and Fergus earlier that day, I'm going to use "he" or "his" to refer to Fergus a lot.
  "Can't believe how close we came to an accident on the way here. We were walking past a building with some scaffolding on it, and a brick just about hit me on the head. Fergus was looking up at the site anyway because his company is advertising on the site, so he saw it fall and stopped me just on time."
  
  You don't use the person's name every time when you're talking about them in their presence.
  Those who appreciate polite behaviour do.
  
  "Can't believe how close we came to an accident on the way here. We were walking past a building with some scaffolding on it, and a brick just about hit me on the head. Fergus was looking up at the site anyway because Fergus's company is advertising on the site, so Fergus saw it fall and stopped me just on time."
  Nobody talks like this
  
  LOL people talk like this. I think perhaps you meant to say that nobody you know talks like this.
  
  maybe i have never been in proper situations, then, because in my experience, people will use pronouns or names indistinctly
  
  maybe i have never been in proper situations
  Indeed. More information on proper communication for you: https://en.wikipedia.org/wiki/Capitalization