This makes sense, but should be considered with the following in mind: reputable sources should be preferred but the initial goal is to see people thinking about sources. Asking newcomers to add a "reputable" source is the next step. Also, not everyone agrees on what is a "reputable source".
This task to discuss about this change.
Message: MediaWiki:Growthexperiments-help-panel-suggestededits-tips-vector-visualeditor-references-main-step2
