Wikipedia has barred citations of The Daily Mail after editors of the online encyclopedia concluded Wednesday that the British tabloid is “generally unreliable.” The decision came after a spirited, years-long debate over the Daily Mail’s credibility among Wikipedia’s active community of volunteer editors. The editors explained Wednesday that the decision stemmed from “the Daily Mail’s reputation for poor fact checking, sensationalism, and flat-out fabrication.” As a result, the Daily Mail and its online offshoot have been “generally prohibited” as a reference on Wikipedia, “especially when other more reliable sources exist.” […] Such a move is unusual for Wikipedia, which has...