No it doesn't, and the request has been declined: Change all @username references in comments when a user changes their name?
It would be easy to implement.
When the comment is written that user name becomes permanent in the comment, clicking the old name still takes one to the correct account with the new username.
There's no reason for old comments to have new names, if someone changes their name to SmarterEveryday does that mean that the comment doesn't contain the best information possible?
What if their previous name was AnimalExpert and they had answered a question about animals - the older name when the comment was written would be more useful than the new name changed after the comment was written.
If/when a pass through the comments is done (to implement that) it saves the need to decide which comment reply applies to whom (since they are not unique), by simply looking up what the user's name was when the comment was written everything will be correct.
Old comments won't have the name-of-the-week, which is hardly useful, and readability would be improved.
But what if you reply to the old name and the user has changed their name, "won't all be lost?" you ask. No, the logic of whom gets the ping won't change (and the punishment transfers to the chameleon, not the reader).
In the infrequent case where someone wants to request to remove a real name it's easy enough for the script to change the name in the comment to userx1234 (instead of user1234), they are unlikely to want the name change and for the old posted comments to be associated.
One thing or another has to give to have the ability to change one's name, comment, or show up late to the conversation. If you have a perfect method to implement it the other Q&A is the place to offer your wisdom.
Because of the ability to have duplicate names, shortened comment replies, and user name changes there's no ability to go forward and update old comments (at least not perfectly and without a huge drain on resource). Going backward and changing the comment's name to what it was when written is possible and restores the sensibility of the comment replies, it's low load but those wanting to reply to visitors old comments will want to click the username to see if it's updated (and they aren't going to answer), much like changing ones phone number but rather than unlisted it is listed just unpingable.