In as much as you rightly said, which I agree that social media promotions normally gains alot of participants,, but also, let's not forget that issue of multiples accounts, some people in a bid to increase their chances of being selected as winners, will join the contest with different accounts, some with up to 10, 20 accounts, inflating the number of participants where as in reality, could just be a few thousands of persons joined, the rest bot or farmed accounts.
Twitter is a big space with huge user community and it is favorite by cryptocurrency enthusiasts and gamblers too. Running promotions on social media platforms like Twitter will make massive noise but impacts for the company will depend on quality of those participants and their works. If they simply like, retweet but don't make their own tweets with good contents, effects would be small. In addition, their followers are important too as they will be users who see activities from those participants.
The company can use Twitter Audit scores to check percent of faked followers and consider it as one of indicators before choosing winners.
https://twitteraudit.com/Organizing something specially for the bitcointalk community would be interesting I believe, but I still wil now fail to try my luck in the social media Contest if I have the opportunity to.
It's good because Bitcointalk is a biggest forum for Bitcoin and cryptocurrency communities. It is a best forum for cryptocurrency accepted gambling sites to advertise their business and products.
