The Sport Accord's definition

SportAccord uses the following criteria, determining that a sport should:[1]

• have an element of competition
• be in no way harmful to any living creature
• not rely on equipment provided by a single supplier
• not rely on any "luck" element specifically designed into the sport

Oxford Dictionary's defintion

an activity involving physical exertion and skill in which an individual or team competes against another or others for entertainment.

And most other definitions include or relate to this

The US and other countries have accepted games such as League Of Legends as a Sport and its discrimination to the Professional Players plus the the Casual Sport watching players these Sports/Games have.