Actually mostly casino's even through online, it's very common and yes a good benefits for all gamblers , especially those who can afford to spend a lot of money coz they can still playing using their rewards.
Comp clubs makes up part of the wins in offline casinos. There have better services to offer gamblers; accomodations, food, etc paid with points gotten from the number of games played. So the players gamble more to win those points. The settings in casinos is to maximize sales, which works.
However, aside the physical designs, the psychology behind a gambler's consistency is money and excitement.