From an in-universe perspective, it would make far more sense for him to create as many Hearts of Azeroth as possible and spread them to as many of the heroes of Azeroth as he could, to ensure we could salvage all of the Azerite that was supposedly bleeding out around the world (even if game mechanics had it only appearing in BfA zones).
God I want to go back to being only one hero of many, and having the game acknowledge that these big threats are met by groups of heroes rather than some lone savior. If I wanted to be the one and only hero, my name would be Link.