Juan Manuel Marquez was the WBA "Super" Champion and the IBF Champion prior to being stripped of those belts. So when Chris John beat him, he beat a man who had been Unified Champion and had never lost those titles in the ring. So while I do not normally recognize a WBA "Regular" Champion's reign as a legit World Title reign. I think it's fair to say that from the moment he defeats Marquez. Chris John had legitimized his reign as a World Champion.
Hard to keep up with these kinds of moments for sure, but since I'm watching Marquez's career straight through now when it gets to the Chris John fight, and Marquez wasn't a defending Champion anymore I was confused.
All this Super, Regular, Interim nonsense is for the birds