https://twitter.com/therealyashsriv/status/1219691914523545601

We shouldn't generate code that might cause browser or linting to complain.

https://github.com/facebook/react/blob/0cf22a56a18790ef34c71bef14f64695c0498619/packages/legacy-events/SyntheticEvent.js#L259

It's also just a confusing pattern at best.
dispatchConfig,
  targetInst,
  nativeEvent,
  nativeEventTarget,
) {
  if (__DEV__) {
    
    delete this.nativeEvent;
    delete this.preventDefault;
    delete this.stopPropagation;
    delete this.isDefaultPrevented;
    delete this.isPropagationStopped;