Riot Games wants is to provide free advertising to League of Legends' competitors. The first thing that the company wants to do is promote the professional gaming side of the community. In the contract for players taking part in the game's 2014 championship series, the company is aiming to kill two birds with one stone by preventing professional players from streaming any competing games during the duration of the 2014 season.
Games considered to be "competition" include World of Tanks, World of Warcraft, Hearthstone, Dota 2, and StarCraft. An official response from the company states that this is comparable to the restrictions placed on pro athletes in several sports. Players in the official Reddit thread are upset by this decision, claiming that the comparison to professional athletes is both inaccurate and inapplicable in this particular context. It remains to be seen whether or not this will impact the game's championship numbers in any fashion.