Comment Wiki
In most internet forums, when a good argument has been made, there is usually a stream of additions and examples provided by other users that end up spamming the thread. Having the ability to edit the original argument allows you to decide whether to add your extension to the original comment or to create a new one.
This way, the new comment is no longer a static step of the conversation but can become a living and growing argument that is supported by its own community of editors.
