This seems to be a best practice, since it is used almost everywhere. However, nowhere is it clearly explained what exactly it does ...

I did find a comment in the [docs](https://emotion.sh/docs/install) that said: 
"This comment tells babel to convert jsx to calls to a function called jsx instead of React.createElement". Does this simply mean it replaces standard React functionality with Emotion's? Are there any consequences from leaving out the /\*\* @jsx jsx \*/ comment?