They do that because they think it makes sense financially. They have a history of trying to corner out the market by trying to force traditionally multi-game

They do that because they think it makes sense financially. They have a history of trying to corner out the market by trying to force traditionally multi-game events into only hosting LoL and not hosting competitors games. They aren't supporting professional gaming, they are supporting their marketing, under the guise of helping out e-sports. This is my opinion on the matter. Riot is also known for many shady business practices, especially with regards to competitors, and they are also owned by Tencent, arguably a company with one of the worst reputations in the world.