Hi!
If an item has no statements, no sitelinks, and isn't used anywhere, how do you tell what it even *is*? The label only? Is that sufficient and/or useful? What would be lost by deleting it? Maybe, if it has labels in many languages, with
Unless its purpose if obvious (i.e. label/description/talk page describes it clearly) I'd say it might be more dangerous to keep it around, as if some people start to use it in different meanings, and then people add independent articles on Wiki which would produce different items with the same meaning, in multiple languages, pretty soon we'd have quite a mess on our hands. Empty item by itself with no links, no good labels and no data or almost no data (like "John Smith, human" and that's it) is not worth much, IMHO.
Yes, I don't have good formal criteria for "obvious" so I imagine we'd have to take it on case basis or maybe think about some.