Sorry, but very poor example. The outcome of the game is decided on things that players have done. There can be occasional disputes over balls and strikes, but you're either out or your not.
Ballet, figure skating, and floor routines are truly a fine art, but not a sport. If you think not, then tell me why ballet is not a sport.
And if ballet is not a sport, then tell me the real difference between the two: Lots of hard work, routines to be memorized, then done over and over again . . . to music on top of it all. Can't find a difference.
I can’t tell you why ballet is not performed as a sport; other forms of dancing (most notably, ballroom) are, though not at the Olympic level.
And the umpires’ decisions, while in most cases clear-cut, do affect the outcome of a baseball game. But it’s really the strike zone, which varies from umpire to umpire (and to hear pitchers and catchers complain, from pitch to pitch!) that has a major impact on what pitches get thrown and their locations, and which dramatically effects the outcome of the game.
In the other sports I mentioned, the style of officiating often can affect how a game plays out. Referees who clamp down on defensive holding allow offenses to air it out more freely in football, while those who let a lot slide result in forcing teams to adapt their game plans accordingly.
So it is with gymnastics, figure skating, etc. The judges don’t directly affect the performance at the time, but the competitors (especially at the top levels) know the judges and what they’re looking for, and adapt accordingly. How is that fundamentally different?