Based on network-wide guidance and a discussion here, we've been actively deleting comment chains that have become obsolete, chatty, or pointless. This has been met with some resistance, in part because of the differing expectations of what comments are for.
We have the following entry in our FAQ:
Can I use comments to discuss the topic of a post?
Comments are useful for getting clarifications, but extended discussions detract from the question and its answers. If you'd like to discuss anything related to programming with other expert programmers, please use our chat room.
But perhaps we can make it better. In a discussion on this answer, it was suggested we highlight the alternatives for disagreeing with an answer where the answerer chooses not to improve it.
What can we do to address this? Are there other things we should address in our FAQ's guidance about comments?