Much better to write a ticket with a vague headings only, assign it to someone and ablate responsibility for everything else to some other person. /s

Generally, if it's not an issue, we wouldn't be talking about it.

If they're asking a question, it becomes pretty obvious within the first few statements if it's an issue or not, even if it's one about missing documentation.

The summary/title of issues can be edited, as needed, and clarifying summary comments can be made.

But you're right, it's not exactly the same. People with language barriers sometimes struggle with "not real time" conversations. Others feel if they're writing something in an issue tracker, it's somehow special, so they have to be incredibly formal, and are afraid to be wrong, ask questions, etc. Some people who are great at speaking are terrible at "slower" forms of communication. I think this does limit those types of people, if you completely close off chat.

Why is this a requirement? You have low quality discussion, in the ether, or you have somewhat constrained discussion, in the issue tracker. You can always "to summarize the above", but if you forget, it still exists where you can find it. At least it's somewhere topically relevant.

Our issue tracker lets us edit other peoples comments. This is nice for linking statements/questions to other issues.