Stuart Elliott: When Publicis Groupe Boss Said "Non," Madison Avenue Listened

There was, for once, big news at the annual advertising festival in Cannes, France, but it had nothing to do with who won the grand prizes.  Er, um, pardonnez-moi, grand prix.  Rather, the 2017 event -- formally, the Cannes Lions International Festival of Creativity -- will be remembered for a startling announcement midway through by Arthur Sadoun, the new Chairman and CEO of the giant Publicis Groupe agency company, that he was bidding adieu for the next year to Cannes Lions, along with other awards shows and events such as CES and South by Southwest.