This seems to be quite the dispute amongst the gamers over various MOBA/RTS titles, but it's not quite often we see word on it from folk who officially work for or manage E-sports. Carmac Who runs Intel Extreme Masters seems to have varying opinions as opposed to famous E-sports figures such as TobiWan or most of Evil Geniuses."So much so that people think that League of Legends wouldn’t have made it as an esports game without it. Well that thought is a big load of crap."
Are the words of Carmac when stating his opinion about the matter. Some could argue that the ridiculous spending of Riot definitely helps artificially "bolster" the scene, and Carmac says more regarding his opinion later.
One of the largest points he argues is that Riot pioneered exposing their casual audience to e-sports, and therefore essentially made it a lot more of an attractive pick for tournament hosts in the large conglomerate of competitive gaming choices.
"I would wager that League of Legends would still be in the major tournaments without Riot’s lavish spending.". Carmac then goes on to explain how a very important component to the circumstantial success that Riot has brought to their game is the fact that the tournaments keep your average Joe occupied when there's nothing to do on League of Legends, or they just don't feel like playing at the time. Idols are formed, and more incentive is made to invest time and money into the game the players love.
However, not all of what Carmac had to say were praises and feats of how Riot is handling it an as e-sport. He states more than once in the article that Riot most likely overspends, and probably doesn't have the experience to run it as flawless as most would like. Though with the phenomenal rate of growth for an infant company, most of the corporations invested in LoL seem to agree that it's worthy of its success and should still be broadcasted by the likes of MLG, IEM, and Dreamhack.
When it really comes down to it, League of Legends is successful as an e-sport because Riot finds a way to offer all of its players as an audience as opposed to just a small few that have integrated themselves into the competitive portions of the game. No doubt a weaker mechanical cap than its competitive comrades, it's a lot more about how the game is presented than how it is played. To close this off, an important quote by Carmac:
"Games are picked for major events on the basis of logical, rational reasons more so than sentiment or individual preference. No game has an irrevocable, divine right to be featured on the center stage just because its gameplay is vastly superior to everything else and its community are the chosen people."
Source: Carmac's World