Why would dark chocolate be worse than any other chocoloate (apart from concentration). If it's truly worse even per piece of cocoa, is it about the cocoa butter?
Cargo culting science: "We tested dark chocolate and it was bad" => avoid dark chocolate and no further conclusions. (Media is full of this pattern.)
More rational investigation: "We tested dark chocolate and it was bad" => Find the problematic ingredient => What are the other places we use this ingredient?
But yes, stories are mass produced and nobody has the time for that.