I don't understand why extended discussions in comments usually get moved to chat. Long threads are collapsed be default, so they don't require significantly more scrolling to get to other content. The comment UI is much more visible, and far more user-friendly, especially on mobile devices. If a conversation gets moved to chat, I basically can't participate anymore, because I use SE from my phone much more than from a laptop or desktop, and chat is basically unusable on the phone.
Stack Exchange is a collection of Q&A sites, meaning Questions and Answers.
Therefore, the main focus, actually the only focus, is the questions and the answers, and that's it.
Anything else exists only to support better quality of the questions and answers, and should be used only for that purpose.
This also includes comments: as the comment textbox placeholder says:
Use comments to ask for clarification or add more information. Avoid answering questions in comments.
While it does not explicitly says "no discussions", it's pretty much implied. Discussions in comments do not do anything towards "ask for clarification or add more information" which is the goal of comments.
Let's take some imaginary example. Suppose there is a question:
I have a code
function doThis(arg1, arg2)however when calling it I get error null pointer exception, how to fix it?
Now, some valid comments can be:
- How exactly are you calling the function?
- What is the code inside the function?
etc. After OP edits with the requested details, such comments become obsolete and can be deleted. That's how comments should be used.
However, suppose someone posting such comment:
I noticed you are from Australia in your profile, I heard life there are good.
Then the OP replies and there's a discussion about the life in Australia. That adds nothing to the question, or to others who are not interested in those things. That's exactly what chat exists for.