Valid reasons for quitting: Physical injury, age-related deterioration of skills (recognizing it's retirement time; should have happened before reaching Tokyo though), yips (mental block that's going to endanger the athlete or adversely affect team effort).

Invalid reasons for quitting: Judges aren't treating me fairly, just not in the right mental space, to much pressure being put on me.

There may be other reasons I haven't thought of in both categories. I haven't followed the story, I'm not watching the Olympics or any other sport these days, so not sure what her actual reason was. Early in this thread it was at least implied that the judges treatment of her was the reason for her quitting.

She apparently has been a great one, too bad her legacy is being tarnished by this. Shouldn't take away from her previous accomplishments.

The biggest problem our country has is not systemic racism, it's systemic stupidity.