I don't necessarily agree. It depends on what the content dispute is about. If there is a 'Church of John Doe' believing that John Doe is the returned Jesus Christ, they might have sources telling that John Doe is the returned Jesus Christ, whereas there are no sources he is not. Does that mean that we have to tell on the Jesus Christ page that he has returned as John Doe? Or if someone claims that between 200 AD and 500 AD the Orkneys were inhabited by a race of highly intelligent orcs, should we include that in Wikipedia as long as noone has taken the effort to explicitly state that it's not true?
I'm only willing to go with your statement if you also allow for 'negative sources' to be counted as sources - that is, sourcing of the type "if this were true and considered important, then one would expect this-and-that source to discuss it, but they don't".
Sorry, by "sources" I mean "reliable sources". An unreliable source is no different from no source.