First, the rules:
- You can always edit youyour own comments for a period of 5 minutes.
- You cannot edit (to be clear, nobody can, except for diamond mods) either your own comments after 5 minute or comments by others (any time), unlike a post.
Now, the justification:
Comments are second class citizencitizens, they are there to serve temporary purposes, like
- asking for clarification
- proposing minor correctioncorrections (to avoid edit conflicts) etc.
A comment, on it'sits own, is not supposed to hold any valuable information. If it is worthy of keeping forever, better to edit the post and add the information in the post itself. Otherwise, the comment can be deleted.