Why do you say that? I'll tell you that there are Russian teams but if it's the competitive scene of Dota 2, these professionals are playing fair and square. Maybe you're talking about the normal matches and rank games? The tournament games can easily be seen on their streams so if somebody is cheating, they can easily be caught by the organizers and even the viewers. Or let us say that there's somebody or a team that cheats during a professional league, they're putting their careers into the pit. And Dota 2 isn't just about them but all regions are involved, SEA, North America, South America, China, EU, and CIS.