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?
Whenever you get judges' results like 98.5, 97, 99.25, and 98.3 from any kind of a panel, you do not at that time have a sport. You have opinions of a performance, and not an honest rendering of the actual performance . . . and that's what it is . . . a performance.
It actually gauls me when people get all choked up over one low result of 4 or 5 panelists and have them consider that a sport.
Baseball is never decided on a panel of opinions.