I guess I found the answer here: Add "Reply" link to comment that pre-populates comment box with @username
I re-posted it below:
We're actually moving away from indoctrinating users into the @username cult for comment replies, for these reasons:
AXIOM: A bunch of comments filled with
@username are harder to read and noisier than those which are not. The goal of our sites is to increase signal-to-noise, not reduce it.
The average number of comments on a SO question is 2.5.
The median number of comments on a SO question is ZERO.
Post owners are always notified of comments on their posts.
If there are only two people talking in comments, the post owner and one other person, we auto-infer replies in that situation as well; that is:
Question? -- User A
Clarifying comment. -- User B
Response to clarifying comment. -- User A
In the above case, A would be notified of B's comment. And B would be notified of A's response to his comment as well. Notice the conspicuous lack of
If the average number of comments is 2.5 -- let's go nucking futs here and assume one of those is a reply from the post owner back to the person who left the comment -- then statistically speaking, @username is not required at all.
For these reasons, I am loathe to perpetuate the idea that people have to use @username at all, except when they need to talk to another commenter.
(Note that I am in no way objecting to an organic mention of someone's name in a comment, in the form of "If you consider blaz, Greg, I think you'll see that fromenting the hogribicator when the z-axis is above 96 degrees is your best option.")