The community doesn't like extended discussion in the comments, nor is the site designed that way:
There shouldn't be useful information hidden in comment threads, it should be visible in the Q&A.
We don't want noisy chats between our Q&A, that's what the chat is designed for.
An explanation from my attempt to have more descriptive messages:
A comment is a remark expressing an opinion or reaction on the question or answer.
Comment threads aren't meant for chatting, conversations and discussion.
If there is a conversation where the questioner is replying back-and-forth on either comment or answer to resolve his problem, the question or answer should instead be improved...
