Unless it's a long-term champ being dethroned, or a draw/robbery, why hold up the division with an instant rematch when we could have new matchups? It's not like Garbrandt or Dillashaw are going anywhere. OTOH, if they rematch, and Garbrandt loses, he's out of the title picture for quite a while unless Dillashaw drops the belt, and any fights he takes just risk derailing contenders. And if Garbrandt wins, TJ gets shafted because nobody would want to see the same two people fight for the belt three times in a row.