If a user name is long enough, we can comment anything to that user
133560
Omit comment replies from the minimum character limit check
26650
Text formatting now allowed in comments (List of proven and disproven abilities)
3237
Require a comment when deleting an answer or a question
90462
Marking comment as an answer?
119457
Would it be better to encourage people to set a user name?
61716
For protected questions, require local reputation to comment
118939
Extend comment "magic links" syntax to allow arbitrary link text
154006
Allow linking (suggested) edits to one comment
68817
How to comment part of a line?
95252
Could new users see a notification in the space where the add comment button would be, like "you need a minimum of X reputation to comment"?
7494
Comment on posts that you have an open bounty on, despite reputation
66719
Can we allow moderators to upgrade a comment to an answer?
20845
Direct Link to a Comment
51535
What's the justification for the commenting reputation requirement?
158765
Tab name completion for comments please!
127922
Why not allow shorter comments?
9269
Let's make it easier to reply within comments!