They are a species born for esports.
When Valve introduced that policy DOTA still wasn't its own thing but a WCIII user made map. DOTA was actually decently popular in Korea but its popularity was soon surpassed by one of the numerous DOTA clones at the time, called Chaos, another WCIII custom user made map.
When Valve launched Dota 2, they introduced the game in Korea as well with Nexon as publisher, but that was after League got its stronghold in Korea.
Well, football wouldn't be of England's making if the Nintendo World Championships played by postcard or small-scale Quake Clan battles could be called esports. We created the whole modern framework, and the Secretary of State for Culture himself adopted the word 'eSports' out of a sea of words - competitive gaming, cybersports, cybergaming, etc.