There's a very old MediaWiki feature: When a page is deleted, a little bit of its content is shown in an edit summary. This is done using "excontent" and several related messages.
It was added by @Eloquence in 2003: https://phabricator.wikimedia.org/rMW8d13af81b7b87f95399dec327a18ba2006e08a85
As far as I can see, some Wikimedia wikis disabled this feature long ago, for example Wikipedias in English, German, Norwegian, and Italian. The reasons for the disabling are not so well documented, but from what the little I can find, people think that it may have privacy considerations, and it's not so useful in general. The disabling was done by blanking the messages in question.
This works, but it raises two questions:
- The method of blanking a message is quite hacky. It would be nicer to make this feature optional using a configuration variable.
- If multiple wikis disabled this feature long ago, then perhaps it's worth considering removing it entirely?