Why does `enterfullscreen` require a user gesture?

In order to make sure all users get a smooth experience, browsers don't allow websites to use the fullscreen Browser API in case the action of using it has not been triggered by a user gesture. Therefore, it is not possible to use the enterFullscreen() Bitmovin Player API call within a player event handler, as its call stack requires a user gesture (e.g. a click) to be present.