I totally agree with this.
These kinds of contests (wagering leaderboard, high multiplier...) are the most effective promotional strategies for attracting gamblers and turning them into loyal customers.
What makes them even more attractive is when they are offered exclusively to a certain community. This makes the community members feel special and know that the casino values and cares about them. They create some kind of social relationship between the casino and the members of that community.
It is true that such contest or bonus offer always have imparts on the community that is was specifically made for, such forster the communication relationship amongst both the casino and the players justa s you have said. This is very strategic in business because it helps to grow a casino and sometimes, gamblers who visits the casino for the first time and as a result of the fair treatment meted on them and other good experience they had with the casino, they might decide to remain with the casino and not go away and some would go as far as referring friends and relatives to the casino and that is home the traffic of the casino keeps growing.