The argument in favor of the edit is: new readers may not read through the whole thread, and you don’t want them stopping at the end of your now-outdated comment and never knowing it was rebutted and that you updated.
The argument in favor of the edit is: new readers may not read through the whole thread, and you don’t want them stopping at the end of your now-outdated comment and never knowing it was rebutted and that you updated.