Beside there is no wagering requirement on this so any new accounts created can easily claim the promo code. I also tried to claim but to no avail. I agree with one of the reply here that without any wagering amount requirement to claim the bonus code, it is also possible that the free spots were farmed by bots.
Don't know at this time but duelbits has implemented this but only for the giveaway code that they spread via their telegram channel, and the terms of the wager req reduce enough abuse because only accounts that meet the conditions can claim it and even the code still works well even though it was posted for a few days, maybe duelbits is just trying to try different ways and the goal is to attract a lot of users to play in their casino.
The goal behind any promotion is to attract new players to the casino and bind the existing one as when they get any kind of promotion through these codes they get happy and wager on the games.The duelbits team is actively doing such promotion and attracting more players to the casino.
You are absolutely correct, it actually baffles me when i see some users who see promotions as bonus, many do not understand the difference, and what some casinos offer to their gamblers as bonus isnt even a bonus but promotion, a bonus is supposed not to come with a any wager requirement since that is supposed to be like a free money given to the gambler for free for their loyalty to the casino.
Promotions on the other hand is a means through which the casino promote their brand, they offer some reward - with a wager requirement, to their players to encourage them to play some certain games, or to sign up and deposit on the casino-for new potential users visiting the casino..
This is just my thought though.