My previous nickname was 0101, I do know it's not just text, because I get alert if some writes @myNickName
P.S. I like to change nicknames once in a while and it's not a BIG bug, just saying.
Actually, it is just text. It is not a special name type object, but a set of string comparisons done against all display names at the time of submission/edit. You can check the full details on comment reply rules here. So in being just plain comment text, it's not a dynamic entry that can just update when your profile changes.
Text update would have a chance for making exceptionally awkward addresses if the reply wasn't the full name, which is common for many users who use names with spaces.
@Grace Note is used to refer to me often, but only the
@Grace actually triggers a reply. If I were to, say, change my name to
Diamond Wedding, then all those replies would end up reading as