User blog comment:ReverseMountain/Bigger, Badder, More Epic- How to top Marineford/@comment-2226235-20160207074118/@comment-9787781-20160207080440

To me it makes sense because, so far in OP we have only defeated 3 of the Shichibukai in the entire series. If Luffy keeps is promise of defeating every single Yonko, and does it individually, OP won't finish ever.