The Jazz have the number one offense in the NBA, saying Donovan Mitchell isn't a real number 1 option is crazy.
The problem Spida has, is that their defense sucks outside of Gobert and they lack a second consistent scoring threat outside of him that can stop the bleeding when the defense is trash and nobody can get the a bucket.
Unless you have a top 5 player in the NBA, you are not an automatic championship contender. And Donovan's archetype, the volume scoring SG, isn't that valuable unless they got a squad around them that can do everything else at a high level or they have a top 5 player as a running partner or both.
In short, Spida's team isn't that good and his skillset isn't that valuable without a great team or a great running mate.
If Spida and Jrue Holiday switched places, the Bucks might win 65 games and the Jazz would be in the lottery.