Some promotions are time sensitive which means the earlier you get the promotion, the better it is for you. On the other hand, some promotions are only listed and offered on the social media handles like Twitter and not announced on the main gambling site or even on this thread. I do not know what is the motive behind those promotions.
Are they meant only for the Twitter followers to grab those giveaways as not all gamblers are following the gambling Twitter handle and some may rarely visit Twitter???
We have seen in the past casinos which give promotions exclusively to bitcointalk members, then it is not strange to see casinos doing the same for other platforms, and if you want to grab those platform exclusive bonuses then you have no other choice but to join it and keep track of those promotions.
Now it may seem unfair to give priority to a platform over another, but if Duelbits has detected that this is an effective way in which they can promote their casino then we must respect their strategy.