While technically the Divine One dies during the blessing ceremony, it is only a temporary condition. The ritual performed by Ruben Ferol and the rest of the council was much more permanent. I'm not sure if there were Divine Ones before that point; there was a League of Seven at the time of the second attack of the Lord of Chaos, but don't know if it was formed directly in response, or some time before. I would assume the Council of Seven was formed to replace the League of Seven after the war, and Divine Ones started after that. For all the searching Ruben Ferol did through history books searching for some way to defeat the Lord of Chaos, nobody complained about the gods not picking a new Divine One.