Dota 2 doesn't have a business model just yet. Valve co-founder and president Gabe Newell says he hasn't even begun thinking about the pricing model. "The primary focus for us at this point is not worrying about monetization, and it's instead worrying about getting the game right," he explains in an interview with Gamasutra.
Rather, he explains that his company's goal at the moment is "on building something that cool" for the legion of hardcore MOBA fans, "and then we'll worry about monetization ... we're not going to worry about that until later." Further pressing the point, Newell adds, "Premature monetization is the root of all evil."
As the interviewer suggests, however, real world economics force many developers to consider monetization models from the design level. Newell sees this more simply. "I think not sucking is way more of an important thing to pay attention to first," he adds, referencing the Dota 2 model of extensive playtesting and iteration before discussing a financial strategy -- a development ideology that works for a successful company like Valve, but may not be possible (or of interest) to other studios. It is a position we can get behind, however.