I propose redesigning the edit conflict merge screen: explaining to the user the nature of the conflict, using special case natural language where possible, and reducing the amount of text displayed to a minimal amount. A word-level merge should be attempted if applicable, and the result displayed for user confirmation.
In certain important special cases, multiple merge options can be presented to the user, allowing them to choose between them without retyping.
For example, say if two users try to insert a paragraph into the same point of an article at the same time. We could have a user interface along the lines of:
> Someone else has changed this article while you were editing it. They wrote the following text at the same place as your own addition.
> They wrote: [...]
> You wrote: [...]
> What do you want to do?
>* Add your text after theirs
>* Add your text before theirs
>* Remove their text, replace it with your text
>* Discard your changes in this area
>* Return to the editor
The last option would return to the editor with with the both the added texts retained and highlighted.