Take these wikipedia articles on Maeonius and Romulus Augustus for example; "According to Gibbon, the murder was revenge for a short confinement imposed by Odaenathus to Maeonius for being unrespectful." and "Orestes, however, refused to become emperor, "from some secret motive", said historian Edward Gibbon"
Forgive me, but it's not clear to me that the examples you cite are of the article using Gibbon as a primary source. Can you clarify your meaning?
In any case, Wikipedia is hardly a "history text," and doesn't keep to the same standards as scholarly writing.