1) If comments are turned off then there is no discussion about the actual job AT ALL.
2) Different people have different opinion about what relates to actual job discussion and what's not.
3) Do you have any tool that can successfully replace comments and facilitate discussion about actual job?
4) Sorry, it wasn't me who downvoted your comment. I disagree with you, but because I value opposing opinions I actually upvoted your comment to encourage to elaborate further.