Comments are often used on this site for discussion, quick hints and even sometimes even more-or-less fully-baked answers. But this is not actually great!
In fact, comments are not for discussion. They are not even for hints. In fact, at least within the domain model of StackExchange, comments are intended only for clarifying the question or answer they're underneath.
In other words: comments should help the asker frame their question. Comments should help facilitate answers. They are not at all for discussion; and in fact, the system already provides such a "third space": the chat engine.
I suggest, with respect to comments, high-rep users in particular need to be thinking about these things. We have to set the tone. Keep chattiness out of comments -- it goes into chat. Hints and partial answers -- should largely go into Answers.
Of course it can be a fine line between clarifying/edifying, but in general I would prefer trying to err on the side of shorter answers than chattier comments. --It's definitely okay to go with a more partial, hint-like or "discursive" answer; especially if the alternative is starting a discussion in comments.
Again: consider bringing some of that energy to chat! Seriously, the chat could be way more fun here given the user base. (The chat mobile interface is not entirely unreasonable.)
Please do consider introducing people to the Chat instead of participating in discussions in comments; and please do consider promoting hints and partial answers in proper Answers. Let's keep comments about clarifying questions.