As far as I know the manager has statement regarding for not launching that contest back again since maybe they are done with it and they didn't get much traffic from that contest or maybe they create new to enjoy their community.
I don't think it was a traffic issue since many members of the forum used to usually participate in those contests. I think that they just felt it would be better to focus on social media sites like X(Twitter) for higher profits.
Yeah the forum specific events were also good way to motivate the community members as many might not feel comfortable in these Twitter giveaways due to bot involvement but we should always try and see if you are lucky or not.
Bots are literally the bane of X. Their pathetic security team sucks at minimising their activity chasing away legit members.